Update documentations.

Update AdminLTE version description.

Merge branch 'master' into 1.5.x

Fixed menu. Added more testing actions. (koftikes#20)

Update BuildAssetsCommand. (koftikes#18)

Fixed sidebar menu.

Fixed bootstrap.min.css.map. Updated components/jquery.

Update README.md

Updated documentations and some extensions. (koftikes#9)

Lock AdminLTE version to 2.3.*