Fade in/out status bar background like a facebook.

Status bar fade in/out when side drawer is open/close for iOS 7.

Closed | Transiting | Opend
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![alt tag](https://docs.google.com/uc?export=download&id=0B7CRbK0yMwIIRFdkR3BfVlhadmM) | ![alt tag](https://docs.google.com/uc?export=download&id=0B7CRbK0yMwIIY3VLbFExYmxRczA) | ![alt tag](https://docs.google.com/uc?export=download&id=0B7CRbK0yMwIIa2U5bEdrT0hlS3c)