Refactor bootstrap/lxc/start.sh

- Use base_aufs option of edeploy-lxc
  https://github.com/enovance/edeploy-lxc/pull/13
  Data are safe now for a LXC deployment
- Refactor start.sh arguments to init, destroy,
  start, stop, restart.
- Comment the /dev/sdb mount of Gerrit that prevent the Gerrit
  node to restart.
- Fix run_functional_tests.sh to handles new arguments

Change-Id: Id1adeb0431e9dc4ce666cbbda46ff8e2c354b039