feat($base.less): Add pull-left, pull-right, center-block
fix($base.less): Fix Typo.
Feat($less): Add text-hide, hide, show, and invisible.
Feat($less): Start Visibility.less
Feat($Visibility): Combine loops into one.
feat($less): Add Visibility Controls.
feat($css): Compile css.
Merge pull request #1 from Echobob/master

feat($base.less): Add pull-left, pull-right, center-block