Calling the addClass, removeClass and toggleClass methods without
any arguments or with undefined/null values, now don't freeze
Zepto
Calling the addClass, and toggleClass methods without any arguments
or with undefined/null values, now don't freeze Zepto.
Merge branch 'master' of github.com:RichardOtvos/zepto

Conflicts:
	src/zepto.js
Fixed the bug if the argument was a null value.
Added the scrollLeft functions
Added tests for scrollLeft()
Merge pull request #833 from RichardOtvos/add-scroll-left

Add scroll left