[devtools] add a 'method' argument to RepoAccess.web_request so that one can easily forge a request with any HTTP method. Also a bunch of clone cleanups.

usr/bin/cubicweb-ctl usr/bin/
usr/lib/PY_VERSION/*-packages/cubicweb/cwctl.py
../cubicweb-ctl.bash_completion etc/bash_completion.d/cubicweb-ctl