submit/tizen/20160114.021519

Graceful exit when wrong file is fed to muxer.

Added null check to output_uri in gst_add_track to return if set_data_sink fails.
Modify mediamuxer to return an error if the media_format during add_track is not matching with med
Update mediamuxer test-suite to return an error if inappropriate A/V codecs were fed.
Hence, user is restricted to feed a container-file with same encoded-media as what he choose durin
Addressed review comments