ffmpeg x265 dependency install

[jblakley]

minor problem in deps.sh. ffmpeg install requires x265 now. In ubuntu 16.04, that requires:

apt install x265 libx265-dev

[jpablomch]

apt install libx265-dev is in the Dockerfile.base.

I will add it to the script for building the staging machine in the AWS Kubernetes example, as well.

Thanks!

[jpablomch]

I have created a new PR to address this issue. Thanks.