Including upstream requirements

Now that internal OSM software does not specify python modules in
setup.py, we need to include the requirements.txt from the module
in the requirements-dev.in to generate the full list properly.

Change-Id: Ieb49e7d276a824a5098c11f9a85d57ddd989b93d
Signed-off-by: beierlm <mark.beierl@canonical.com>