fix  $.isFunction in Nitro/V8

 typeof a RegExp will returns "function" in Nitro/V8
fix $.isFunction in Nitro/V8

$.isFunction returns ture for a RegExp in  Nitro/V8.
Think about fix the problem in this way?
Merge pull request #180 from jieyou/master

modify the mothod for $.isFunction $.isArray and $.isObject