Adapt Debian versions to new format

The pre-release suffixes (such as .dev0) are not Debian version specific
but belong to the upstream LinOTP package.

Change-Id: I93355e5ef1aa715664a1aef45c3d505e093e496e
Remove VERSION from linotp Makefile because it is unnecessary

Change-Id: Ia3c4e7653adf9d4dea566a8f6c6c37ce5588dad8
Use package __version__ in adminclient scripts

Change-Id: Ia3fa6979046435e0909ebb9debe8968806c1438b
Adapt preprocessor.ini to changes in internal build tools

* Version information is extracted directly from the source files (e.g.
  debian/changelog or setup.py)
* AdminClient script files use the package specific __version__
* Other files containing versions need to specify a regular expression
  that allows updating this version

Change-Id: I6e0de486be7e5bf652da7491a5fc2454b516d64f