WIP: first prototype of the JSON API.

 * Tests not included, so I cannot prove that it works
Add 'revision' attribute to Conference, managed by an observer
json API for suseconferenceclient
Merge pull request #12 from ancorgs/master

JSON API for https://github.com/athanrous/suseconferenceclient
Adding and removing people
Speaker is displayed instead of submitter un public pages
Speaker can be changed in admin/conference/x/events
Merge pull request #14 from ancorgs/feature_addpeople

Manually adding people and changing speaker for an event
Merge pull request #13 from differentreality/event_registration

Event registration
Fixing a slightly broken table in events list
Fixing the json generated by admin/conference/x/events
Merge pull request #15 from ancorgs/feature_addpeople

Fixing a slightly broken table in events list
Merge pull request #16 from ancorgs/master

Fixing the json generated by admin/conference/x/events
admin adds new user/person and registration
add nick and affiliation
error messages
attended field as true in new registrations created by admin
create migration for adding field 'attended' in registrations table
add pagination, re-arrange view
add option to delete registration