Pull changes to collect domain fronting dialing stats

Closes getlantern/lantern#1913  Includes changes that require changes on the Java side, see https://github.com/getlantern/lantern/pull/1921
Does it matter if the updatesCh blocks on send?  Do we believe this buffer size should always prevent that?

If this is a concern at all, a way not to have to commit to a buffer size would be to always report in a goroutine and make this unbuffered.