feat(grunt): new 'serve' task

- add livereload on the builded gh-page
- fix the existing watch task
style(jshint): first global strict correction

 - boss : "Use '!==' to compare with 'null'"
 - globalstrict : "Missing 'use strict' statement"
style(jshint): Mixed double and single quotes correction.
fix(mark): TypeError: input is undefined
style(jshint): remove unused variables
fix(ui-scroll): 'setOffset' is not defined.

I have no idea of what it supposed to do.
I fixed it by returning the value given in the function argument but I bet that it's not the behavior we want -_-
fix(ui-scroll): 'isArray' is not defined.

I guess that we want angular.isArray here
fix(ui-scroll): 'newitems' is not defined.

Must be a typo