Add DB schema version info

Part of #122.
Change nipap.conf defaults

Moved nipap.conf to nipap.conf.dist. We will let Debians postinst script
generate the configuration instead or have the user copy the file and
manually edit it.

Part of #122.
Don't ship clean.plsql

It just doesn't make sense..
Add debian configuration scripts

This will have debconf ask the user questions to configure / setup
nipapd. At this point, two actions are supported;
 * if nipapd should be started upon system startup
 * Automatically configuring postgresql for NIPAP

In the future the idea is that this script will help with upgrading the
database structure and similar things as well.

Everything to keep installation as smooth as possible.

Part of #122.
Ignore clean.plsql
Set correct DB version

Part of #122.
Back out incorrect change
Improve nipapd.postinst logic somewhat

Part of #122.
Add debconf to dependencies of nipapd

debconf is not part of Debian essentials so we need to make sure it's
installed before nipapd can be properly installed.

Part of #122.