Correcting problems on attachment permissions

Also removing some superfluous haml syntax and css styling
Add one test for attachments
Prevent crash when sending invitation for conference room
Small translation
Improve permissions for Attachments a bit

Users that upload an attachment and then leave the space shouldn't be able
to destroy the attachment.
Also added a few more tests.
Starting some changes to make better the way to search for users in manage page
Add option to disapprove user and admin options in users/edit

Now users approved can be easily disapproved by admins.
Admins have also access to all the options that were previously only on
mange/users when they are editing a single user at users/:id/edit

refs #953
Finish the filter of users in manage/users

Included a new js component called ResourceFilter. Used in pages where the user
can type in a text input and filter the results shown in the view, as is done
now in manage/users.

refs #958
Implement filter of spaces in manage/spaces

The same filter that is used in manage/users, see ffe8582bbc.
Also improved the way the view looks and fixed/verified both UsersController#enable
and SpacesController#enable. Some links and some logic were wrong before.
Added tests for everything.

refs #958, refs #957
Merge remote-tracking branch 'upstream/branch-v2' into branch-v2

Several conflicts, see below. Had to adapt some controllers and their tests.
Some things are still not 100%, made the minimal changes to make the tests
pass.

Conflicts:
	app/assets/stylesheets/app/manage/users.css.scss
	app/controllers/manage_controller.rb
	app/controllers/users_controller.rb
	app/views/manage/_enabled_user.html.haml
	app/views/users/edit.html.haml
	config/locales/en/mconf.yml
	config/locales/pt-br/mconf.yml
	spec/controllers/manage_controller_spec.rb
	spec/controllers/users_controller_spec.rb
	spec/models/user_spec.rb
Several small improvements in institutions and management pages

- Adapting the management lists of users and spaces after the last merge with upstream/branch-v2
- Very basic institutions/spaces view
- Set an institution object directly in User, not only by name

refs #951, refs #1058