Changing to stable debian (wheezy).

Therefore it compiles agains more common version of GLIBC.

Now works out of the box on Debian wheezy, centos:centos6 and other stable
Of course it works on new distributions. Tested with:
    debian:jessie and
    ubuntu:14.04

Signed-off-by: Alexander Holbreich <alexander@holbreich.org>

Conflicts:
	Dockerfile
Run pyinstaller build as normal user

... and test build on CI so we don't break it again!

Fixes #503

Signed-off-by: Ben Firshman <ben@firshman.co.uk>
Merge pull request #505 from bfirsh/use-debian-wheezy-base-image

Compile against older version of GLIBC
Add versioneer

It's a clever versioning thing which means we don't have to manage
versions. It'll magically read the version from Git tags and
generate useful development version numbers.

https://github.com/warner/python-versioneer

Signed-off-by: Ben Firshman <ben@firshman.co.uk>