Add Makefile target for automatic version bump

All the Makefiles for the different NIPAP components now have a new
target called 'bumpversion'. It will bump up the version based on the
content of the NEWS file in the project root. sed and the new
news2dch.py script is used to update individual files containing version
information and the debian/changelog respectively.

Fixes #435. This actually accomplishes more than we originally set out
to do with #435 but I guess that is ok ;)
Explain how to search using tags

This adds a brief text on how to use tags when searching for prefixes in
the web-ui.

Fixes #439.
Merge branch '439-search-help'
Auto-update debian config & postinst script

Makefile target 'bumpversion' will now update the database version in
the debian package scripts 'config' and 'postinst' so that these are
aligned with what is in the nipapd database file. The nipapd.config
script has been out of sync which caused the prompt to update the
database to be displayed when it is actually not needed.

Fixes #424.
Merge branch '424-debian-script-prompts-twice'