get_device_warnings is gone; netOrk names the warnings from facts
(netOrk #1111). get_hypervisor_hosts() reports each host's connection
state, maintenance mode, configuration issues and managing vCenter;
get_licenses() the assigned licenses with the edition key as edition,
never the key itself.
The reach stays: the ESXi driver reports connected as None (a
disconnected host could not have answered), and managed_by only for a
host it reached directly. parse/warnings.py is replaced by
parse/hosts.py and parse/licenses.py.
