Remove RHEL specific code from Debian init script

It didn't make sense to have this code since the entire init script only
supports Debian systems.
Use default instead of set

`default` is the preferred method of setting attribute defaults.
Add more global settings

Add ability to configure more global settings via attributes.
Allow multiple listeners to be customized

Previously we only allowed ZNC to listen on one port, and there was
nothing that could be customized. Now each port can be individually
customized.
Add more supported options for user config

Allow individually users to configure more files.
Allow users to configure networks

Add more granularity to the individual user configuration options.
Don't require per-user Buffer

Allow user config to fall back to default max buffer size.
Bump version to 0.0.3