Multiple instances support

An increasingly often requested feature, multiple schools on one server.

The scripts, make-schooltool-instance and start-schooltool-instance, need new options, defaults, and search locations, to support creating/running instances defined in /etc/schooltool, in addition to current directory.

For example,

  $ bin/make-schooltool-instance --prefix=/var --sysconfdir=/etc tuxville

would create an instance in /etc/schooltool/tuxville with database in /var/lib/schooltool/tuxville and logs in /var/log/schooltool/tuxville

Then,

  $ sudo start-schooltool-instance tuxville

Would start the tuxville instance from /etc/schooltool/tuxville, unless there is "tuxville" in current directory.

When installed in Ubuntu,

  $ sudo make-schooltool-instance tuxville

Will create instances in the aforementioned locations by default.