Version changes for release 0.9.0.
Merge pull request #418 from pwendell/0.9-versions

Version changes for release 0.9.0.
Merge pull request #420 from pwendell/header-files

Add missing header files
(cherry picked from commit fa75e5e1c50da7d1e6c6f41c2d6d591c1e8a025f)

Signed-off-by: Patrick Wendell <pwendell@gmail.com>