Fixed bug in #webconference find method.
Now users are find by their userID.

#refs 721
Attempt to test #webconference method.
(not working properly).
Fix matching of attendees in SpacesController#webconference

And the missing tests.

refs #721
Fix the displayed duration for recordings

Now when the recording has just one playback format, a single duration time will be presented, when have more formats, a list will be presented showing the duration of each format.

refs #1147
Make title and users mandatory to send webconf invitation form. refs #1364
Some tests for rooms#send_invitations , some pending
Improve hints for space permalinks

refs #1379
Tests and refactor for feedback controller
Block joins if the room's limit of participants was reached

Acts as a 'soft limit'. Blocks joins if the limit was already reached.
It works well but can't be considered a hard limit since multiple concurrent
joins might end up exceeding the limit.

(Code pulled and adapted from a private mconf-web fork.)

refs #1385
Allow admins to edit BigbluebuttonRoom#max_participants

refs #1385
Move ability classes to separate files
Add brakeman gem and rake task to run security checks
Remove possibility of using non specified locales
Merge branch 'master' into Bug1147
Use :vague time_ago_in_words, don't want it always too precise

refs #1147
Add dotiw locale for en

The gem already adds it, but seems weird to have it for pt-br but not for
en. No problem having it both on the app and gem, though.

refs #1147
Cleaner views to show playback links and duration of recordings

Less text, with focus on the links and the duration. Made it look good both
on the list of recordings and when recordings are shown in the list of
recent activity.

refs #1147
Remove unused strings from locales

refs #1147
Update bigbluebutton_rails and improve names for playback types

Also added code to generate the new structure of playback types on
db:populate.

refs #1147, refs #1142
Update bigbluebutton_rails to improve playback links

Order playback links, showing the default always at the top. Include the
duration only for the first playback link, since they should all have the
same duration. Also improved a bit the dates shown with the recordings.

refs #1142