Fire input events when identities are added and removed to keep the onscreen appearance in sync.
Summarize the audience of an encrypted file on the save screen.

Introduces miniLock.util.summarizeAudience(audienceIDs, sessionID)

Probably, this function should be located on miniLock.UI, but since its not included in the test suite I put it on miniLock.UI so that I could exercise it with tests.