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: I3b3eee1b7a88c4d0b14b7c8966769c3918ad77e0
Signed-off-by: beierlm <mark.beierl@canonical.com>