ffmpeg: update to 2.1.3

Signed-off-by: Timothy Gu <timothygu99@gmail.com>
ffmpeg: delete some useless configure options

Signed-off-by: Timothy Gu <timothygu99@gmail.com>
ffmpeg: enable gnutls

Signed-off-by: Timothy Gu <timothygu99@gmail.com>
libbluray: update and fix update script

Signed-off-by: Timothy Gu <timothygu99@gmail.com>
ffmpeg: update to 2.1.4

Signed-off-by: Timothy Gu <timothygu99@gmail.com>
Add documentation of `make update-checksum-*`

Signed-off-by: Timothy Gu <timothygu99@gmail.com>
Add documentation of `make update-package-*`

Signed-off-by: Timothy Gu <timothygu99@gmail.com>
Merge pull request #333 from TimothyGu/stable

ffmpeg and libbluray updates and fixes