BugFix:  FileRequestHandler - Set the response Content-Type header to a default value of text/html if we don't find the right content-type for our file.
This way we don't throw an IllegalArgumentException and kill the server.
Added a test image.
Added a test message for getting images.
Images return proper MIME type.
ResponseBody now works on byte arrays, not strings.
The ResponseBuilder now returns byte arrays.
Updated tests for the new ResponseBody and ResponseBuilder interfaces which work on byte arrays rather than strings.
Server will now return images properly.