DDF-407 added in the returning of the filename in the Content-Disposition http header (inline; filename=<filename>).  Also cleaned up the error handling so it didn't return stack traces or package names and set the proper content type when sending back errors (text/plain)
DDF-407 added unit tests for read method.  Still need to add unit test coverage for the other methods
[DDF-456] Switch to slf4j in ddf-content
[DDF-456] Remove a left-over bit of log4j
[DDF-456] Fix missing parameter markers.

Thanks to Matt Ramey for pointing this out during review.