Simplify PostCreator - Introduce TopicCreator

Extract code to smaller methods
Add 'login required' site setting
Redirect all controllers to login if required

We want to skip the filter for sessions controller so that we can login
and we want to skip the filter for static pages because those should be
visible to visitors.
Redirect to root after login if no path provided

If we do not do this, then people that login from /login will just be
redirected back to the login page. We'd rather have them see the root
path.
Show login modal on header buttons if required
Redirect Ember routes to login if login required
allow onecase switch
Merge pull request #955 from novemberkilo/master

Reduce complexity of PostCreator
Merge pull request #957 from chrishunt/chrishunt/lock-down-the-base

Add 'login required' site setting
es translation is bust, rename for now
missing skip filter for omniauth
Remove static navigation from login page
fix encoding for category excerpt
fix missing secure category topics in categories page
fix blank created_at .. date is unbound, we should rename it to unboundDate
Redirect to '/' if OmniAuth login from '/login'
Allow customization of 'login required' message
message format is awesome, remove 0 unread and 0 new links.
Merge pull request #959 from chrishunt/chrishunt/login-required-fixes

'login required' site setting improvements
speed up test
we need to be able to do username checks for registration to work