UP-4142 Group import changes

https://issues.jasig.org/browse/UP-4142
https://issues.jasig.org/browse/UP-4159
https://issues.jasig.org/browse/UP-4160

Changed crn script for group and group membership import to allow changes to group membership to update caches.

To do:  
* Test in clustered uPortal situation to verify imports on one node clear caches on other nodes
* Test if ant import-data will flush caches on uPortal nodes (optional but desirable)