Adds invitation by email to events

`initializers/mweb_events.rb` now loads controlers and models from `lib/mweb_events/`

`lib/mconf/invitation.rb` is now a generic class for invitations. WebconfInvitation and EventInvitation
implement more specific stuff

refs #1216
Invite button opening modal + some translations

refs #1216
Refactor common behavior of invitations a little more

refs #1216
Correct authorization for join_request actions
Views and controllers to restore join requests behavior
Refactor and add some join_requests tests
Move abilities tests out of space controllers and only ensure authorizarion is called refs #1172

Conflicts:
	spec/controllers/spaces_controller_spec.rb
Prevent i18n deprecation warning
Auhtorization tests for user controller
Some tests and pending tests for join requests
More tests for join_requests controller and some fixes
Tests for join requests invite and create?invite=true and correct some failures
Update rspec-core to correct a bug
Use coverage with COVERAGE=true in the test command line
Make should_authorize really work by not calling extra code
Slight refactor join requests controller refs bug #1252
Remove ability tests from controllers (user/spaces) and assure this doesnt hurt test coverage
Authorization tests for manage controllers
Send email after join_requests are created with some tests refs #1252
Remove spork gem