Being able to access inherited property for JS class

[victorteokw]

This commit add support for accessing inherited property.
Unit test added, too.

Also,
this commit add a launching screen, have it being able to support iPhone 5 screen.
And the iOS demo get a much nicer background color.

[bang590]

@cheunghy Seems that you make -getProp: and -setProp:forKey support the original property, but this two APIs should only use for custom property in JS, the original property already has API to get and set, I think self.setTitle("t") is better than self.setProp_forKey("t", "title").

[victorteokw]

Oh, I see.

[victorteokw]

So you may close it since this PR is not valid anymore.

[bang590]

@cheunghy thanks