DDF-382  updated CachedResource to save num bytes read as size of resource;
updated RESTEndpoint to populate Content-Length HTTP header with resource size
DDF-382  added PostQueryPlugin to set resource-size of
each metacard in query response results to cached file
size if available
DDF-382  added more unit tests
DDF-382  added check for cache entry having associated product and unit tests for this
DDF-382  added temporary sleep for CachedResourceInputStream to be available to RESTEndpoint
DDF-382  moved setup of FileOutputStream for cache file to increase performance