objfilter

#objfilter

##Usage

var objfilter= require('objfilter');
var obj={a:1,b:2};
var result= objfilter(obj,['a']);
//result=={b:2};
var result= objfilter(obj,['a'],'w'); //'w' for whitelist and 'b' for blacklist, default blacklist
//result=={a:1};