Update README.md

Update author list for 0.2 release

depends: Do not download libva debs for non-x86

docs: How to switch to libusbk backend

tools: Add mkcontrib.py

Merge pull request #530 from xlz/release-cleanup

Release cleanup, fix memleaks, packaging helpers.

Merge pull request #507 from xlz/preemptive-api-expansion

Preemptive API expansion

Merge pull request #450 from alberth/cmake_doxygen_config

Add doxygen configuration and target to cmake