This adds a basic robots.txt which prevents indexing of pages under
`/groups`.

2728 misc annotation controller refactors part 2

This one needs to be of the `var` form because it gets redefined later.

Better for each property to have its own docstring where it's defined,
than to try and keep them in sync.

This function isn't part of the view model, it's never called by the
templates, only by code in annotation.js itself.

Move the public method vm.render() out of AnnotationController, making it a
private function and renaming it to updateViewModel().

This function is not part of the view model (it's never called by the
templates, only by code in annotation.js and tests) and its tests don't need to
be part of the annotation controller/directive tests. Move it out.

All the function does is copy some fields from the domain model to the view
model, the opposite of what the updateDomainModel() function does, so rename
it to updateViewModel() and put it next to updateDomainModel(), clarifying its
role.

Private functions first, then public methods, and each section in alphabetical
order. This also means that all `on*()` event listener functions are together
(except for vm.onKeydown()).

Also always use the `function foo() {}` form instead of mixing it with
`var foo = function() {}`.

Public properties first, then private ones, then event listeners and watchers,
then initialization logic, and each group in alphabetical order.

Also added/improved some docstrings.

It isn't necessary.

Collect all AnnotationController init code together in an init()
function. Previously it was spread around at the top, middle and bottom
of the AnnotationController() function, some of it even hiding between
method definitions. Now it's all in one place.

Remove USER_CHANGED event from AnnotationController

Add groups report to admin dashboard

When the user logs out or logs in we throw away all the
AnnotationController instances and create new ones. So everything it
needs to do "when the user logs in" (or out) AnnotationController can do
on Initialization, it doesn't need the event.

Refactor saving highlights in AnnotationController

Remove the global variable `annotation` from annotation-test.js.

This paves the way for having different helper functions for creating
different
kinds of annotation and passing them in to the directive initialization.

Some describe()s still use their own global annotation objects, these
should be
factored out as well.

Simply having no content does not make an annotation a highlight (it
also has to not be a page note or reply).

Clarify the logic a little.

* Rename local variable `highlight` to `newlyCreatedByHighlightButton` and add
  a docstring - clarify what this piece of state actually means.

* Fix `vm.isHighlight()`: It now returns `false` for new annotations that the
  user hasn't entered any text or tags for yet (instead of `true`).

* Move the code for saving new highlights to the server into a
  `saveNewHighlight()` function that's called on AnnotationController
  instantiation instead of having it in a `$watch()` function that's called
  every time the local variable `model` changes.

  Also use the presence of `model.id` to avoid re-saving highlights that have
  already been saved - instead of abusing the `highlight`
  (now `newlyCreatedByHighlightButton`) variable and confusing what it
  represents.

* Don't automatically open the annotation editor on Annotationcontroller
  instantiation if the annotation is a highlight. This fixes this bug:

  1. Create a new highlight while logged out
  2. Log in
  3. Your highlight is saved to the server, but also the annotation editor is
     open on your highlight.

  The intention is that highlights are simply saved to the server, not opened
  for editing.

  _Annotations_ created while logged out, on the other hand, are _not_ saved
  to the server on login but _are_ opened for editing on login.

Refactor annotation controller tests

Remove gloval `controller` variable from AnnotationController tests.

Move the tests for annotation.js's top-level function out of the
'AnnotationController' describe() - these functions aren't part of
AnnotationController and their tests don't need all the setup in this
describe().

Wrap the annotation directive tests in a new top-level describe that's
for the entire file annotation.js, not just AnnotationController or the
annotation directive.

Refactor annotation controller, part 1

Move scope.feature() from the annotation directive to vm.feature() in
the AnnotationController. Just trying to move as much as possible out of
the directive's scope and link function into the controller, if we're
gonna use a directive controller here try to just use it instead of
randomly using the link function and scope for some things and the
controller for others.

It doesn't appear to be possible for model to be null.