v3.1.0

Changelog:

c03b12c Dockerfile: Switching from MAINTAINER to LABEL.
7c0cb7d mount_lockbox: do not discover CLUSTER name
b7df2c3 variable: do not test for fqdn if not necessary
5c63f9d variables: do not use 'hostname' command
24bd34a rgw: read config startup from ceph.conf
a9bdf2e mon: backward compatibility with fqdn configuration
0e7c95a rhel7: remove wrong label format
2723bc7 rgw: allow override RGW_FRONTENDS
c0b7f18 rhel7«: make Dockerfile linting happy
e9b9609 tests: update python requirements