Fix for OVPMS-1500 Reversal of supplier invoice produces incorrect balance

git-svn-id: svn://svn.openvpms.org/openvpms/archetypes/branches/1.8-dev@6278 9e4fa352-aafb-0310-9071-df624684024b
Fix for OVPMS-1462 Check for unique user name before saving users

git-svn-id: svn://svn.openvpms.org/openvpms/archetypes/branches/1.8-dev@6279 9e4fa352-aafb-0310-9071-df624684024b
Changes for OVPMS-1521 Change to the Calculation for Line item Price

git-svn-id: svn://svn.openvpms.org/openvpms/archetypes/branches/1.8-dev@6280 9e4fa352-aafb-0310-9071-df624684024b
Changes for OVPMS-1501 Add support for rabies tags 
Comment out the rabies tag identity so it doesn't appear by default.

git-svn-id: svn://svn.openvpms.org/openvpms/archetypes/branches/1.8-dev@6306 9e4fa352-aafb-0310-9071-df624684024b