Merge remote-tracking branch 'origin/branch-v2' into branch-v2-refactor-emails

Conflicts:
	Gemfile
	lib/mconf/digest_email.rb
	lib/mconf/invitation.rb
	spec/factories/join_request.rb
	spec/mailers/notifier_spec.rb
Remove unnecessary call to JoinRequest#send_notification

Notifications for join requests are now send via resque scheduler from
recent activities.
Show recent activity items for join requests
Several small improvements in the emails after PR #26

Most notable: removed the unused model Informer, renamed the mailer Notifier
to ApplicationMailer, renamed the ApplicationMailer to BaseMailer.

refs #371
Refactor the feedback email and the tests for ApplicationMailer

New feedback email and form, using haml, simple form and everything else we
use in Mconf-Web v2.

Tests for mailer methods should only test that the email returned has the
correct properties and body set. Tests that the mail is sent/enqueued should
be made elsewhere. For the digest_email, for instance, the test that it is
enqueued is at spec/lib/mconf/digest_email_spec, since this is the class that
actually calls the "deliver".

refs #371
Remove test for the already removed model Informer

refs #371
Move invitations to the database to work better with resque

Invitation objects were being passed to mailers to format emails. With resque,
ideally only the identifiers should be passed to the mailers, that should then
fetch the objects. Moved the invitations to the database so we can do it.

refs #811, refs #371
Invitations are now sent by a resque worker

An Invitation object is created for each invitation sent (one invitation per
user) and sent in background by a resque worker.
With this we have a record of all invitations sent and whether it was
successfully sent or not.

refs #811, refs #371
Merge branch 'branch-v2-refactor-emails' of github.com:mconf/mconf-web into branch-v2-rails4

Conflicts:
	Gemfile
	db/schema.rb
	lib/mconf/invitation.rb
	spec/factories/join_request.rb
	spec/mailers/notifier_spec.rb