fixed bug in request mixin

Added matchSelector helper

removed __xtagnodeinserted__ event for the faster element.contains() …

…to determine if node is in DOM

renamed bindMethods to bindMethod, fixed setAttribute for safari<6

added __DOMComponentsLoaded__ event

updated readme

Update x-tag.js

null reference fixed

fixed keypseudo bug

throw error for undefined pseudos

allow devs to mutate a value inside a setter and pass that value to s…

…etAttribute