fix(bootstrap): upgrade angular-ui-bootstrap
feat(private-messages): start implementing private messaging (includes blocking). Start experimenting with reflists for PMs, instead of arrays
Merge pull request #4260 from HabitRPG/PMs

Private Messaging
refactor(private-messages): cleanup block-user
fix(members): add a callback so members modal doesn't popup until after
member is fetched
fix(private-messages): blocker can't message blockee
fix(private-messages): clear newMessages both when leaving and entering inbox
feat(private-messages): add a "clear all" button
fix(private-messages): glyphicon-ban-circle (@Alys @crookedneighbor)