Dockerfile: Add repo manually

* Add the bitcoin ppa repo manually instead of installing a number of
  packages to accomplish the same thing.
* Results in a leaner container and builds slightly faster.
Dockerfile: Undo hacks to fix perm issue

* Remove the hacks that attempted to fix a permission denied issue with
  the trusted builds from index.docker.io.
* Comment on how to fix it.
bootstrap-host: Add script to fix broken host machines

* Primarily fixes Ubuntu 14.04 droplets on Digital Ocean because 1GB of
  RAM isn't enough and the Ubuntu docker pkg has permission issues.