Basic camera reading.
Updates to AVDevice files
Camera updates

* libav requires "video4linux2", not "v4l2" (ffmpeg takes both)
* fixed empty exports in libavdevice_h.jl files
Merge pull request #13 from kmsquire/kms/camera

Basic camera functionality
Updated README
Added a versioninfo().
Merge pull request #16 from lucasb-eyer/master

Added a versioninfo().
Updated README to make optional dependence on Images.jl clear
Update to VideoIO.jl

* Use new BinDeps features like library groups
* Update build incantations for new versions/platforms
* Remove all postproc stuff
* update REQUIRES

Edit: disable {av,sw}resample, other minor additional updates (kms)