Adds support for raw yuv files for 422/444

Adds support for raw yuv inputs in 422/444 sampling for use
in profiles 1 and 3.
New options added to vpxenc are:
--i422 and --i444, which are to be used in conjunction with
--width, --height, and --fps for proper raw yuv handling.
A new option is added to vpxdec:
--rawvideo, which enforces raw yuv video output for the
bit-stream decoded irrespective of 420, 422 or 444 sampling.
The existing options --i420 and --yv12
are specialized for use only for 420 content.

Change-Id: I2e3028380709afa673bf2e2c25ad5e271a626055