Update FilterPaneService.groovy

Fixes jira issue 
http://jira.grails.org/browse/GPFILTERPANE-99
Update _filterpaneSort.gsp

Fixes jira issue 
http://jira.grails.org/browse/GPFILTERPANE-92
Upgrades to 2.2.1 and added maven pom to allow maven building
Suggested change to solve GPFILTERPANE-104

Makes it possible to supply your own valueMessagePrefix to a g:select while providing values to it.
Merge pull request #3 from ascheffe-umd/ars-2.2.1-upgrade

Ars 2.2.1 upgrade
Create README.md
Merge pull request #4 from stenix71/patch-3

Suggested change to solve GPFILTERPANE-104
Merge pull request #2 from stenix71/patch-2

Fix for GPFILTERPANE-92