Notification of membership requests not implemneted

[rbaertsch]

If a user requests membership in a collaboration. The owners should be notified.

[e-t-k]

Alex is administrator of a collaboration.
Blake requests to be added to that collaboration.

Actual behavior:
On Alex's view of that collaboration's box on /collaborationList a button appears: "Review 1 request".

Expected behavior:
The button appears.
A notification appears in the notifications area in the top bar.

On page /account, under email notifications, there is a checkbox for "Join requests for collaborations I administer." If this box is checked, in addition, Alex receives an email notifying them of the request and linking them to /collaboration-review for that collaboration.