Ignore .egg-info files when building debian packages.

I was having a problem where py2dsc was dying because
it was trying to generate a diff that was including the
.egg-info directory setup.py was creating.

It turns out Arnaud Fontaine <arnau@debian.org> had the same problem
and suggested a fix -- to add extended-diff-ignore to debian/source/options

Fixes deb#657611
Fix overly nested directories

The first four lines fix a regression introduced by
18af4d6325050c24106d8f9ebd8baad124b36af6.  The rest
removes an unnecessary conditional and unindents the
block.
Replace any newlines or repeated whitespace in the description with a single space.
README: add link to dh-virtualenv
remove outdated check for no-longer-used functionality
fix test script to deal with multiple .deb files
py3 compat: print function
py3 compat: calculate md5sum
py3 compat: ConfigParser
remove '--force-buildsystem=False' as an option
py3 compat: exceptions
py3 compat: import xmlrpclib
py3 compat: string handling
py3 compat: integer conversion
py3 compat: absolute imports
generate .changes file when building source package. Closes GH-37.

Note that to upload to a PPA you will still have to sign the .changes
file.
remove '--force-buildsystem=False' as an option

Forgotten from commit 6488dede7778bf2326d7c80471d1bb769b817cf2
slight improvement to docs
rely on travis only building branches with .travis.yml

Don't bother blacklisting branches.
pypi-install: convert from OptionParser to argparse module