Directly install requirements with pip

Rather than parsing then feeding the pip requirements file to pip,
just have pip consume it directly.

Change-Id: I17bbe4324e6957c7165bc0f340ddae1e51039471
update for name change to Neutron

Note: Nova and Horizon are not updated until those projects have
migrated.

Change-Id: I256ef20e7caadd9c96e6dd908c5d8b69ca5c4aeb
Merge "Directly install requirements with pip"
Merge "update for name change to Neutron"