Add optional metadata to initiliaze the render threat.

The render threat is likely to break your application if you initiate it.
As such it must be explicitely requested using the following meta-data
tag in your manifest's application tag:

<meta-data android:name="android.graphics.renderThread" android:value="true" />

Change-Id: Ibf0a48af2a0d091562bf6907eac970e3d1d601c4