Update to Angular 1.5.6 (#3443)

This brings support for lifecycle hooks which get called when components
are mounted, when their inputs are changed and when they are destroyed.

See https://github.com/angular/angular.js/commit/9cd9956d

Angular patch releases have historically been pretty safe WRT breaking
changes, so this loosens the version strictness slightly.

package.json

@@ -4,13 +4,13 @@
   "version": "0.0.0",
   "description": "The Internet, peer reviewed.",
   "dependencies": {
-    "angular": "1.5.0",
+    "angular": "~1.5.6",
     "angular-jwt": "0.0.9",
-    "angular-mocks": "1.5.0",
-    "angular-resource": "1.5.0",
-    "angular-route": "1.5.0",
-    "angular-sanitize": "1.5.0",
-    "angular-toastr": "^1.5.0",
+    "angular-mocks": "~1.5.6",
+    "angular-resource": "~1.5.6",
+    "angular-route": "~1.5.6",
+    "angular-sanitize": "~1.5.6",
+    "angular-toastr": "^1.7.0",
     "angulartics": "0.17.2",
     "autofill-event": "0.0.1",
     "autoprefixer": "^6.0.3",