Use > CSS selector.

This patch will resolve inner scrollbar problems.
No longer support old IEs.
Bind touch handlers only when it's supported.

Fix #227.
Stop propagation and prevent default for touch events.

Fix #228.
Add additional information to package.json
Release 0.5.4

1. Inner scrollbar problem fix.
2. Inner scrollbar touch event problem fix.
3. Bug fixes.
Update README.md

Add `npm` to install section.
Merge remote-tracking branch 'upstream/master'