In mapmos, made the default for the TYPE parameter BANDNUMBER because, when...

In mapmos, made the default for the TYPE parameter BANDNUMBER because, when running the GUI and PRIORITY=BAND, a blank type= was added to the command line string. This no longer occurs, there is either no TYPE parameter or it is set to type=keyword. In ProcessMosaic, Modified the GetBandIndex() method so that the returned band index is consistent whether the band number or the band keyword is used as input. Fixes #1549.

git-svn-id: http://subversion.wr.usgs.gov/repos/prog/isis3/trunk@5131 41f8697f-d340-4b68-9986-7bafba869bb8