cef: move arguments for cef build into inc file
cef: add proprietary_codecs=0 and ffmpeg_branding=Chromium to cef build system
cmake: add switch for h.264 support

v2: add H264_SUPPORT documentation
ebuild: add useflag for h.264 support
cmake: add WITH_FLASH option
ebuild: add useflag for flash support
Merge pull request #505 from karolherbst/h264

add h.264 support, but disable it by default