Do fewer things for a dev installation.

If the development parameter is passed to the install-script, don't
install a crontab, don't set up nginx, don't force the repository
to a particular version, and don't set up an application server.

Also only create a general.yml file if one doesn't already exist,
and add some locales that the test suite assumes are present.
Example Vagrantfile and notes.

Based on previous work on vagrant branches, adjusted to use the new
--dev argument of the install script.