camera: Add support for sending raw commands

 * Certain camera drivers need magic commands to select special modes
   such as ZSL or HDR. Add support for sending raw commands from
   applications.

Change-Id: I512a765c7a67ffd2877e465cf6493ffc2b3b54ac
Merge pull request #14 from adgad/jellybean-legacy

camera: Add support for sending raw commands