fix dependencies in packaging
This fixes up dependencies to be more correct.
The net result is that after 'apt-get install curtin', then
curtin --install-deps will not have any work to do.
curtin-common changes:
- drop 'python' from curtin-common package as it does not use any python.
- util-linux >= 2.20.1 is in all ubuntu (precise+) so remove this
dependency as util-linux is 'essential'
python-curtin, python3-curtin:
- drop 'curl' from dependencies of python-curtin or python3-curtin
this was simply incorrect. wget is used, but curl is never.
- explicitly list the python dependencies on oauthlib and yaml
the attempt to have dh_python resolve these was just simply not
working. so explicitly list them.
requirements.txt:
- urllib3 is never used, drop it from here.
- pbr is not needed. (it was probably copied from cloud-init)