Some refactoring for User Manager and added user status during add/update
Some refactoring for User Groups manager
Fixed user activate/deactivate in admin
Changed the user status message 'Activated/Not Activated' to 'Active/Inactive'
Changed the directory names for Slideshow modules to be in title-case
Bug fix: Permissions for modules cannot be saved
Merge pull request #35 from masud79/user-status

Some enhancements and fixes related to user management