Debian packaging cleanups

Hello,

A couple of us at freedombox project are looking to have pagekite in Freedombox (https://freedomboxfoundation.org/). For this, we first need to upload the pagekite package into Debian repository for this. However, in the current state pagekite's debian package is not uploadable to several non-standard practices in it.

I understand that upstream pagekite wants to automatically build debian packages from makefile similar to rpms. Keeping this in mind I have made several changes to the way debian packages are being built. This work should also help you build packages that fit well into a Debian or Debian derived distribution.

Finally I have made a change to rename the debian/ directory to deb/ at the suggestion of a Debian developer. In the makefile a link is created from debain/ to deb/ it works are usual. This is done so that we can maintain a non-native (separate from upstream) packaging setup in our repository in debian/ directory. This makes maintaining non-native (for uploading to Debian repositories) setup and changes easier.

The following are the highlights of the my changes:
- Make debuild work on source without any prior make steps
- Automatically generate changelog entries when version changes
- Make the debian package a "native package"
- Update standards version and fix most lintain warnings.
- Remove CDBS, modernize python build process using debhelper + pybuild
- Minimize "git status" junk entries after a build using git ignore.

Please consider merging these changes upstream. If not the whole, consider taking whatever peices you can; I have really taken care to keep my commits small. I am available for queries or additional work at sunil at medhas dot org.