OPAL-2270 - implemented password change for users who are in opal-user-realm
OPAL-2270 - refined error handling
OPAL-2270 - removed enums and added exceptions instead
OPAL-2270 - removed password logic from resource to service
Merge pull request #449 from kazoompa/bug-OPAL-2270

OPAL-2270 - moved logic from resource to service