Identity JS sign in user trigger
Fix Id JS module being init twice
Tests for Identity JS sign in trigger
Test for Identity JS sign in return URL trigger
Merge remote-tracking branch 'origin/master' into identity-signin-trigger

Conflicts:
	common/app/assets/javascripts/bootstraps/app.js
Reorder ID init in Identity bootstrap
Merge pull request #2454 from guardian/identity-signin-trigger

Identity sign in trigger