More complete list of salt dependencies.
Configure salt master and minion services.

We're moving to pip, which unlike the apt installer, doesn't do
this for us (but allows us to pin versions other than latest.)
Get lib-cloud from pip.

salt-cloud 0.8.9 requires a newer version than apt provides.
Replace salt-cloud's bootstrap script with one that installs from pip.

This is so we have control over the version we install in minions, for
reproducibility.
Parameterize salt version in config.py.
Fix for Salt 0.16.0, upgrade version.