add login/logout flow (bug 907886)

Redirects to a login view if not logged out.
Redirects back to the main view ```comm``` when logged in.
Redirects to the login view after logging out.

Perhaps add the login.html to Commonplace?

![screen shot 2013-09-04 at 1 58 33 pm](https://f.cloud.github.com/assets/674727/1083993/c894c318-15a4-11e3-8fc7-a02bc627e997.png)