Add an easy way to add cancel buttons in modal windows

Edited the "f.button :wrapped" extension made for simple_form to work better
when used in modal footers.

Also added the default "cancel" button to several modal windows.
Always return an activerecord relation on spaces/index refs #1166
Show the number of results in the management list of users and spaces refs #1083
Default to images on space logo uploads and don't duplicate recent activity for logos. refs #978 refs #1049
Update ruby to 1.9.3-p484

The gem debugger was causing a few problems, so it was removed. It had not
been used for a long time.
Update bigbluebutton-api-ruby and bigbluebutton_rails
Add tests for 13017cd3

refs #1166
Fix spaces/index for anonymous users and adjust its visual

Made it look better and with more information for anonymous users.
Add signal in spaces/show when a user is member of the space

There was no easy way to tell if you were already member of the space you
were accessing or not. Added a small text in the page title.
Lots of improvements in join requests

Cleaned up the views and the controller.
Improved the messages shown to the user when dealing with join requests.

With this we are a bit further on improving the way join requests are shown
to the user, see #1067

refs #457, refs #1067
Fix the modal to create and edit news
Refactor private_messages/new to use select2

It also pre populates the input with the user selected, it any. With this we
can click a link to send a message to an specific user and the select2 input
will be automatically set with this target user.

Had to improve a bit the route users/select to search users by id.

refs #275
Merge remote-tracking branch 'upstream/branch-v2' into branch-v2

Conflicts:
	app/assets/stylesheets/app/spaces/index.css.scss
	app/views/spaces/_list_view.html.haml
	app/views/spaces/_space_thumbnail.html.haml
	app/views/spaces/_thumbnail_view.html.haml
	config/locales/en/mconf.yml
	config/locales/pt-br/mconf.yml