Merge branch 'v1.3' of github.com:cocos-creator/engine into v1.3

Merge pull request cocos#1299 from knoxHuang/v1.3

fix load bug for #fireball/issues/4739

update engine version to 1.3.0

Merge pull request cocos#1063 from knoxHuang/v1.2

fix anti-alias error