Add missing Build-Dependency on python-pkg-resources.

This fixes a FTBFS.

Thanks: Sven Joachim <svenjoac@gmx.de> for the hint
Closes: #713835
Fix misplaced README.txt.gz.

Thanks: Sven Joachim <svenjoac@gmx.de> for the patch.
Closes: #713834
Update changelog.

Git-Dch: Ignore