INT-3122 Return String Properties as String

Make converted object toString() behave as expected
INT-3132 Add minSubscribers to Pub/SubChannel

Send is deemed to be successful if sent to at least this
number of subscribers (default 0).

Note: when using a task executor, if there is at least one
subscriber, a send is always good, regardless of success
or failure of invoking the handler.

Polishing - Docs - PR Comments
[artifactory-release] Release version 3.0.0.M3
Revert Version to 3.0.0.BUILD-SNAPSHOT