Make bootstrap scripts work more reliably

* Set -e so that we don't continue blindly ploughing on after an error.
* Don't try running services that have not yet been installed
* Fix some incorrect string escaping in vagrant/bootstrap.sh
* Fix environment variable setting in vagrant/bootstrap.sh (appending to
  ~/.bashrc doesn't work for scripts, since .bashrc starts with
  `[ -z "$PS1" ] && return`)
* Remove verbosity from unpacking archives
Merge pull request #18 from ept/bootstrap-scripts

Make bootstrap scripts work more reliably