Keep awxkit's requirements on the setup.py

awxkit's setup.py was making use of pip internal structures to parse the
requirements.txt file. This is not a good thing as they may change,
actually that just happened.

To avoid this in the future, move the list of requirements to setup.py
and make requirements.txt list `.` as the only item. This way we keep a
single place to update requirements in the future and avoid accessing
pip's internals.

awxkit/requirements.txt

@@ -1,2 +1 @@
-PyYAML
-requests
+.