Snap support part 3

[patviafore-kudzera]

Allow snapcraft to build anywhere -- don't assume it's running on LXC.

Launchpad Build farms set up a different structure for snap builds, so replacing lxc paths like /root/project with the correct environment variables

Before submitting a pull request:

• Did you fork from the development branch?
• Are you submitting the pull request to the development branch? (not master)