Update codeigniter to 2.1.4
Change version in README
* Rename Admin_Controller for better convention style.
* Restructured login functionality to private method.
* Used new refresh function in AJAX.
* Added new helper methods for controllers.
* Removed controller for manage migrations, the migrations now is autorun.
* Admin_Controller file call after declare the class.
* Added drop table for prevent errors if the users table already exists.
Corrected grammatical errors for README, remove migrations instruction.
Added Public_Controller for extends migrations functionality.