CLC-4011: Update gems: SASS / Compass / Foundation / Font Awesome / RavenJS / Angular Rails Template & remove gem: placeholder

https://jira.ets.berkeley.edu/jira/browse/CLC-4011
Merge pull request #2728 from christianv/CLC-4011

CLC-4011: Update gems: SASS / Compass / Foundation / Font Awesome / RavenJS / Angular Rails Template & remove gem: placeholder