Remove comments from requirements.txt (workaround pbr bug)

Workaround for pbr bug https://bugs.launchpad.net/pbr/+bug/1191923

Change-Id: Icfb4e1f7036e8df69223e3dda63b42a823ac7cd4
Signed-off-by: Paul Belanger <paul.belanger@polybeacon.com>