The driver only checked if the corresponding value was in the config, so
no_dns: False
had the same effect as
no_dns: True
Change the check to take the value into consideration.
This makes false-y values like False (from YAML) and empty string
(from environment) work as if the value was not specified.
Tests modified to comply with PEP8 rules with exception of rule E501 (long lines).
Done by autopep8 tool and 2 manual modifications.
https://fedorahosted.org/freeipa/ticket/3744
Heavily inspired by code from xmlrpc tests.
To obtain ranges, this patch also adds method to execute FreeIPA command through Web UI.
It uses Web UI instead of ipalib so it doesn't need to care about authentication on a test-runner machine.
https://fedorahosted.org/freeipa/ticket/3744