Add a basic whois server

Query by prefix or text string and receive prefix results and relevant
VRF information.

Part of #344.
Add search for prefix in VRF to whoisd

The whoisd now supports searching for a prefix in a VRF by specifying
RT:prefix. 123:123:1.2.3.4 would search for 1.2.3.4 in VRF with RT
123:123.
Add config file & daemonize to whoisd

Config parsing, pid file, daemon stuff and so forth ripped from nipapd.

Part of #344.
Add default config file for whoisd

Part of #344.
Add man page for whoisd

Part of #344.
Add readme file for whoisd

Part of #344.
Add setup.py for whoisd

Had to rename nipap-whoisd to nipapwhoisd as it is not impossible to
import files with a dash in them.

Part of #344.
Restructure whoisd

It's not possible to import files not ending in .py so I split up
nipap-whoisd into a "lib" module which doesn't do much except for
holding our version info and some supportive functions.

Part of #344.
Add makefile and debian packaging

nipap-whoisd can now be packaged into a debian package by our Makefile
just like we do with our other components.

Part of #344.
Add nipap-whoisd to main makefile

So that it can be built together with the other packages!

Part of #344.
Add init file for whoisd

Init file, mostly copied from nipapd and with a default file.

Run as nobody:nogroup per default.

Part of #344.
Add config/postinst rules for whoisd

Ask whether nipap-whoisd should be automatically started or not.

Part of #344.
Fixes for whois daemon

Handle socket startup errors.

Call the right function for dropping privs - was moved into nipap_whoisd
lib but reference not updated. Same thing for __version__

Move binding to socket to before we drop privs.

Chang pid file location. We cannot share with nipap as they are run by
different users (per default at least).

Part of #344.
Merge branch 'master' of github.com:SpriteLink/NIPAP
Merge branch 'whois-server'