This is already unconditionally installed via install_apache_uwsgi in
stack.sh; we don't need to install it again in keystone. Since we
need workarounds on some platforms (see
I3bc5260e77cebe852cc8d70d9eddf84ef71d74bb) we only want to do this in
one place.
Change-Id: I40d84cbdf68cf6bb5cba143b6c0c126cdb8a84d4