Prevent saving an empty call forward destination

git-svn-id: http://fusionpbx.googlecode.com/svn/trunk@6853 e2954ef0-caed-11de-bd98-e341d93cc3cc
Prevent an empty call forward destination

git-svn-id: http://fusionpbx.googlecode.com/svn/trunk@6854 e2954ef0-caed-11de-bd98-e341d93cc3cc