GIF: add a few more things to the metadata table

See
http://lists.openmicroscopy.org.uk/pipermail/ome-users/2013-April/003662.html

Conflicts:

	components/scifio/src/loci/formats/in/GIFReader.java
Merge pull request #520 from melissalinkert/gif-metadata-stable

GIF: add a few more things to the metadata table (rebased onto dev_4_4)