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
New uploader with progress bar on space logo
New uploader for user logo
Make space#update_logo work with cancan
Translations for uploader and some corrections
Single test for profile ability
Merge branch 'branch-v2' into branch-v2-uploads

Conflicts:
	app/models/abilities.rb
	spec/models/space_spec.rb
Better look for uploader and more custom options
New uploader for attachments
Use json format for uploader endpoints refs #1273
Merge branch 'branch-v2' into branch-v2-uploads
Rename some javascript variables and use handlebars for uploader
Refactor crop after the new uploader
Test profile update_logo ability
Correct participant register error text. refs #1221
Remove extra and wrong button to register for events after e06e08864c

refs #1221
Simple feature test for pending join requests
Call authorization tests for join_requests controller