Switched to much simpler setuptools based packaging and install process
and remove the old configure script and makefile.

Notable changes:

* The version is now taken from a lightweight git tag. Things will
  be broken until we put the tag in the repository.

* data/* has been moved into src/* so we can use it as package data
Added .gitignore
Teach setuptools to build our console scripts for us. On windows
this automatically generates the necessary files so this can invoked
directly from the command line (does Rubber even work on windows?)
Change module location so that now we can invoke rubber directly
from the source tree. The scripts for doing this are:

bin/rubber
bin/rubber-info
bin/rubber-pipe
Made version detection a little more robust to failure. Just report
UNKNOWN and issue a warning if the version information is missing.
Re-enable installing man pages.