Merge pull request #514 from sergeyklay/master

Mango updates
Merge pull request #515 from sergeyklay/master

Added Session_Mango - MongoDB-based session class
Merge pull request #516 from sergeyklay/master

Improved Model base class
Updated Issue #373: Removed system/view
Updated feature: Improved File::getUnique. Now file name is optional
Fixed issue: Fixed PHPDoc
Fixed issue: Updated PHPDoc & minor fixes
Fixed issue: Cleanup code, cleanup PHPDoc
Updated Issue #373: Cleanup gleez/view