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
pypi-install: pass CLI arguments to py2dsc-deb
pypi-install: allow --help without being root
emit py3 binary package
optionally emit python 2 or python 3 packages
document Python 3 in README
bugfix
add --no-python2-scripts and --no-python3-scripts options
document '--no-python2-scripts' and '--no-python3-scripts'
specify dependencies for python 3
default binary package depends on python version. Closes GH-56.

If Python 3 is being used to call sdist_dsc, the default option
is --with-python3. This seems consistent with the common expectation.
Merge branch 'py3'