Merge pull request #270 from knowledgepoint-devs/modal

TYPE_ACTIVITY_ASK_TO_JOIN_GROUP is an Activity.activity_type that's being used to create Activity objects but it's not been included in that field's choices tuple! It is now. This means that in the admin list view of Activity model we can now filter by this activity type.
Merge pull request #273 from knowledgepoint-devs/modal

**This requires css fixes** Fixing auto-refresh for user profile group add, exposed group removal button which works well but needs css fixes (fixed for KP but not askbot). Also added latest step to site setup instructions.