Update machine configuration

- Change kernel image type to uImage
- Select preferred provider for jpeg to libjpeg-turbo
- Select preferred version for libav to 9.%
- Remove usbgadget from MACHINE_FEATURES
Remove unused kernel config frament am335x-bsp.cfg
Update kernel 3.14 bbappend

- Add custom device tree support
Add files used by linux-ti-staging_3.14.bbappend
Add multimedia image

- Includes video reader packages
Add mplayer2_git.bbappend to enable this package