Revert "Revert Channel locking change, needs testing on stage"

This reverts commit cd0794ae744cbdc868f3dc7a9cb23154d9d748ae.

Conflicts:
	src/main/java/org/atlasapi/remotesite/bt/channels/BtChannelGroupUpdater.java
Add multiple BT channels environments
Merge pull request #601 from atlasapi/channel-writer-lock

Ingest multiple BT channel configurations