Remove upstart dependency.

Debian prefers sysvinit, which is supposed to be compatible.
Point to updated buildpack for wheezy.
Add sysvinit support for Debian distros.

Can't get upstart to work on Debian 6 and 7. Plus, they don't like you to change their process manager.
Fix PORT_NUM substitution.
Fix master sysvinit script.
Fix tests.
Do not forget to start master service when scaling up.
Simplify chroot command.