Refactor jshint files.

We'll use grunt, and jshintignore is useless.
Remove comments in jshintrc to be parsed in grunt.
Add node_modules in gitignore.
Remove build shell script.

We'll use grunt to build the scripts.
The shell script is no more used.
Csslint the css file.
Add csslintrc.
Add files for Grunt.
Minify source files with the new build system.

From now, the build can be done with 'grunt build'.
Update README.

The link to Contributing wiki page is added.
Add a sample based on text content
Add feature to suport ie.

For ie browser, the `.ps-container` element will add extra class `ie`
and `ie<version>`, like `ie6`, `ie7`, `ie8`, etc.

Use scripts to add '.hover' class on the `.ps-container` and both scrollbars when then mouse is over them.
$el.outerHeight() or outerWidth() retrive an incorrect value

This make the contentWidth or contentHeight has an smaller value. And produce an longer scrollbar.
This is happening in xp sp3 ie7. This is perhaps caused by the 'hasLayout' problem. Add 'zoom:1' to the first child will solve the problem.
Can not scroll the scrollbar when the mouse is over the blank area.

Happened in the xp sp3 ie7/win7 ie10. If scroll the mouse over the blank area, the scrollbar will not move. See the example 'text-content.html' I committed.
Also you can find the scenario at http://jsfiddle.net/crocodile/TAkhM/15/
and http://jsfiddle.net/crocodile/TAkhM/16/

Add an 'background-image: url("about:blank")' to solve this problem.
Fixed the scrollbar height for xp sp3 ie6

set 'font-size:0' for the scrollbar
Add a sample based on text content
Add feature to suport ie.

For ie browser, the `.ps-container` element will add extra class `ie`
and `ie<version>`, like `ie6`, `ie7`, `ie8`, etc.
Add hover handlers for ie6.

Use scripts to add '.hover' class on the `.ps-container` and both
scrollbars when then mouse is over them because :hover is not supported
except 'a' element.
Fixed the scrollbar height for xp sp3 ie6

set 'font-size:0' for the scrollbar
Separate the function updating the css of scrollbars.
Fix ie6 scrollbar position problem.

This patch is in fact contributed by the idea of @maoziliang.
Merge the patches of @maoziliang.

Includes IE fixes.