This fixes some issues with pyflakes:
AttributeError: 'ClassDef' object has no attribute 'keywords'
Add requirements for six>=1.7.0
This is for jaraco.collections but something is draging in an older version.
Change-Id: I4733fb4be29463ae6dbfef1ecfb80b0aa8b45e5c
Signed-off-by: Paul Belanger <pabelanger@redhat.com>