Added the ability to create rate-targeted, temporally
scalable, VP8 compatible bitstreams.

The application vp8_scalable_patterns.c demonstrates how
to use this capability. Users can create output bitstreams
containing upto 5 temporally separable streams encoded
as a single VP8 bitstream.
(previously abandoned as:
I92d1483e887adb274d07ce9e567e4d0314881b0a)

Change-Id: I156250a3fe930be57c069d508c41b6a7a4ea8d6a

this was excluding all .asm files when it should have just been .asm
files in the top level directory and .asm.s files lower down. also be
more restrictive on some other items, and run the whole thing through
sort to keep it organized

Change-Id: Ia48525033226b13098a491ce89465d0377b990c2

Change-Id: I653ff5062660bc35cfc8a99d176e36d3d63bae20