FLUID-5542: Queued DataSource

Added a Queued DataSource that can combined with different requestQueues to synchronize, throttle, and debounce requests to a DataSource.

http://issues.fluidproject.org/browse/FLUID-5542

This is an extension of the work started in https://github.com/fluid-project/metadata/pull/43
I had been following this example http://benalman.com/projects/jquery-throttle-debounce-plugin/ but I'm not sure I fully understand your comment, particularly about the amalgamation. I don't think there are currently any provisions to ensure that requests are merged together.