Add config_supportAutoRotation.

On some products, it may not make sense to use the accelerometer
to perform auto-rotation.  In that case, the product's config.xml
framework resource overlay should set config_supportAutoRotation
to false.

Setting this to false also disables auto-rotation settings.

Bug: 13211999
Change-Id: If9d7d72f2a2c576b14a4ff0afb61ea52c42c3357