Begin adding frontend tests for the new AccountController code that
deals with the new form for changing the logged-in user's email address.

I've done this as a new top-level describe() with a new way of writing
Angular controller tests, rather than adding to the stuff already in
account-controller-test.coffee.

The aims of this way of writing tests is to make the tests easier to understand
and modify (either to fix a broken test or to add new ones) by:

- Reducing special Angular knowledge needed to understand the tests

- Reducing globals (both global variables and beforeEach() functions) used in
  tests.

  These increase the "travel" needed to understand a given test method because
  you have to read the whole test module to understand everything that happens
  before the test runs and what all the global variables the test uses are.

  The aim is that reading only the test function (and not the rest of the code
  in the file) should be enough to understand the test.

  Similarly I shouldn't have to read and understand the whole test file to add
  a new test.

  Globals and beforeEach()'s also tie the tests together. For example if a
  bunch of stub services and a controller are created in beforeEach() functions
  then any new tests added to the file inherit this stubbing behaviour even
  though they may not want it or may need something else. This again makes
  changing or adding just one test harder - need to understand the whole file,
  changes made for one test may break other tests.

Implementation notes:

- Used a new top-level describe(), didn't want to inherit all the globals,
  beforeEach()'s and stubbing of the existing one.

- Because we now have two top-level describe()s had to use a try ... catch in
  the second one to avoid creating the "h" Angular module twice.

- Tried to decouple the tests from Angular as much as possible, reduce the
  amount of Angular knowledge (especially about providing and injecting
  dependencies) needed to understand the tests.

  Angular's $provide isn't used at all, and inject() (which I don't think can
  be removed completely) is contained in two helper functions.

- Rather than a beforeEach() and global variables we use a controller()
  function that creates the AccountController and stubs for the services it
  depends on and returns an object of all of them.

  Tests can then call controller() and use destructuring assignment to get only
  the bits they need.

  Every variable used in a test method is defined in the test method
  (sometimes by calling a helper function and getting a return value).

- controller() by default uses minimal stubbing, but the caller can optionally
  pass in their own object for each of the stubbed dependencies.