Changed the handlebars helper registration

The latest ember release requires these changes, because there is no
_rawFunction property on helper functions anymore...
Removed the last non-native Promise calls
Updated ember and other dependencies

Also fixed various errors and deprecations related to the ember update.
WIP: Some things are still broken and need to be changed/fixed...
Fixed userAuth issue with unresponsive API

Never delete the auth record if the twitch servers are offline
Fixed bindings issue of InfiniteScrollRouteMixin
Reworked SearchbarController
Merge remote-tracking branch 'upstream/master'