[GEOT-4802] Creation of two new processes called BandMerge and BandSelect.

Please look at the following JIRA: http://jira.codehaus.org/browse/GEOT-4802.

Note that the pull request also adds the "it.geosolutions.jaiext.roiaware" string as JAI Authority inside the gt-referencing module. This has been done in order to accept the JAI-EXT operations.

JAI-EXT is an extension of the JAI API with new operations and some modifications on old operations (No Data support, optimization and so on). Currently there is not an official release of JAI-EXT, so the dependency to the JAI-EXT bandmerge module, which is used by the "BandMerge" operation, has been included inside the Unsupported modules.