CYB-397 Remove some caching for Nico

* removal of some cruft, initial attempts to cache

https://jira.ets.berkeley.edu/jira/browse/CYB-397
CYB-396 - Engagement index: unable to sort by "Last Point Earned"

https://jira.ets.berkeley.edu/jira/browse/CYB-396

The fix is to upgrade to AngularJS 1.3.7:
https://github.com/angular/angular.js/blob/master/CHANGELOG.md#137-leaky-obstruction-2014-12-15
Merge branch 'CYB-396'
CYB-395 - Choose between `sr-only` or `dc-visuallyhidden` CSS class