* SyncTarget now persists the remote timeline after pushing to it.
* Added SyncTarget.shutdown() to allow callers to signal the sync timer thread
to stop.
* Fixed a bug where a SyncTarget was added instanciated times.
Web timelines as defined by the JDB Labs Web TimeStamper tool are now supported.
* `TimelineSource` now also takes the timeline config file as constructor input.
* Refactored `Timeline` to use reduce implementation redundencies: internal
implementations do not duplicate functionality.
* Improved comments in `TimelineProperties`.
* Updated `TimelineSourceFactory` to handle timelines that need to use
`JDBLabsWebTimelineSource`.
