Added support for box-sizing border-box

Added a fix for the width-calculation in case of 'box-sizing' 'border-box'. (padding doesn't count on top of the width in this case, so I set the padding to 0)

Would resolve these two issues:
https://github.com/vitch/jScrollPane/issues/27
https://github.com/vitch/jScrollPane/issues/180
Merge pull request #246 from pieht/patch-1

Added support for box-sizing border-box
Updating header comments and re-minifying after 2ab86338a95958d17cc2cca8d3d19a47c6166f18

Fixes #180 and #27
Merge branch 'master' of https://github.com/vitch/jScrollPane

Conflicts:
	script/jquery.jscrollpane.js