use AR counter cache for to cache the count of classifications
ensure the latest user_group : user classifcation counts
Validate user login presence
Case insensitivity for User login and email
add user_group to classification association with a cached_counter
Conditional password length validation for migrated users
Fix issue #30

Use new instead of create so URIName is created in the same transaction
as its parent model
Merge branch 'feature-user_validations'
Merge branch 'bug_fix-uri_name_transcation'