Add a loading indicator to team members tab

See #2213 

Edit: As a note, this updates libsass to 0.3.0.  The version we were using previously was choking on `@keyframes` and `@-webkit-keyframes`

Loading:
![](http://9k1.us/MkTu/Screenshot_from_2014-03-31_19:50:09.png)

Loaded:
![](http://9k1.us/tIfr/Screenshot_from_2014-03-31_19:51:04.png)