Add validation for signin/signup

Closes #2976, Closes #3017

- Move logic to signup controller
  - Add ValidationEngine mixin to signup controller
  - Add signup validator with code from clientold login view
- Add signin validator and integrate into signin controller
- Add validation to forgotten controller
  - Switch to button action to support hitting enter in text field to submit
- Clear all notifications in notifications.closeAll
- Modify ValidationEngine.validate to not format errors based on option
- Update casper test for signin to wait for notification before trying
to do another signin
Merge pull request #3051 from jgable/loginValidation

Add validation for signin/signup
Ensure incomplete tags aren't lost on save

closes #2991, references #2172, references #2453
- moved and separated tags logic from EditorTagsView into PostTagsInputController/View
- call out to PostTagsInputController when saving post to ensure an incomplete tag is completed before save
- added Tab key support for suggestion selection / tag completion
- don't show suggestions list when input field doesn't have focus
- added code for #2172 but left commented-out as it causes side effects with completion on save
- updated suggestion highlighting so it doesn't bork on html/regex chars (#2453)
Uncomment signin validation test + test cleanup

closes #2989

- classing this as finishing the casper tests for now
- adding a name to the description in the settings template
Merge pull request #3061 from ErisDS/issue-2989

Uncomment signin validation test + test cleanup
Close notifications on transition or user action.

closes #3012
- Inject notification object into router
- Listen to didTransition / observe currentPath to close notifications
- Close notifications on successful save actions
Use transitionToRoute in controllers.

refs #3051
Merge pull request #3005 from kevinansfield/ensure-incomplete-tags-arent-lost

Ensure incomplete tags aren't lost on save
Prevent notifications from being too tall and unclosable

Closes #1558

- Adds a wrapping tag around the notification message
- Change tests to look for new wrapping tag

For the fix to work properly, it needs styles from the [0.8 branch](https://github.com/TryGhost/Ghost-UI/commit/b98029911c4695f17cb9d05bc48ca5e8eeb77bf6) of Ghost-UI
Merge pull request #3058 from halfdan/3012-close-notifications

Close notifications on transition or user action.
Merge pull request #3059 from PaulAdamDavis/1558-notifications-ui

Prevent notifications from being too tall and unclosable
Merge pull request #3062 from halfdan/transition-to-route

Use transitionToRoute in controllers.
Language cleanup in update check disclosure
Merge pull request #3063 from JohnONolan/pg

Language cleanup in update check disclosure
Enable validation for settings/general screen

Closes #3036 Refs #3012
-Enable validation for settings/general
-Turn on functional tests for the validations
-Move notification closeAll calls so that notifications
 are cleared on attempted saves instead of just on
 successful saves