Changing GWT and GXT version.

GWT update to 2.6, GXT update to 3.1.0 beta. Had to modify a LOT, currently only login panel is displayed.
Figure out how to add panels ... ? Anže, Matej? o.O?
Added LoginPanel.
Fixes to GUI, work on AbstractRegistrationForm.
Fixes to GUI, work on AbstractRegistrationForm.
Registration form ported to GXT 3.0 (without storing to database yet)
Registration form completed. Working.

Also supported confirm password field. Supported check for duplicate user.