use scrollHeight & scrollWidth to avoid getting the wrong size of the content
Remove $content.

It's not used anymore.
Modify README.md.

The requirement that force just one content element is gone.
JSHint the code.

Missing space.
Fix the wrong indents in example pages.
Inhance the scroll logic with mobile touches.

The scroll works only when the user touch and scroll the wrapper div
with just one touch. By this patch, the zoom function will not be
prevented by scrolling content.
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
Fixed the scrollbar position for xp sp3 ie6

The bottom of scrollbar-x and the right of scollbar-y just keep the static value 3px.