Support IPv6 in address check lookups.

This supports IPv6 in address DNS lookups and socket bind checks. Addresses are
looked up with the system getaddrinfo(), and the v6/v4 preference of this lookup
is respected. IPv6 address literals in the config file are expected to be
bracketed in [], and the result of lookups will be bracketed as well, to support
the ZeroMQ URI format.
Unset the IPV4ONLY socket option if available.

Since IPv6 sockets support both v4 and v6 addresses, the socket option is unset
unconditionally if the parameter is available in the zmq module. The actual
decision as to which address version to use is done by the address lookup code,
which obeys the system v4/v6 preference.
Be more resilient towards missing addresses and hostname lookup failures.
Add a unit test for passing IPv6-formatted addresses to verify_socket.
IPv6 address literals should be specified without brackets in config files.
Clean up some PEP8 stuff
support comparisons for IPv4Address
Reduce timeout's by a third.
Remove unused code.
Define the local client a bit latter. Refs #1935.

This seems to fix #1935. It also fixes the issue we had in which the test-suite would not finish properly it would just hang.
Merge pull request #4559 from s0undt3ch/hotfix/fix-travis-again

Fix travis again
Merge pull request #4560 from ahammond/support_comparison_for_ipv4

support comparisons for IPv4Address
Merge pull request #4561 from s0undt3ch/hotfix/fix-travis-again

Fix tests.
Add CLI for consistency
Add examples to the docstrings in `salt.modules.dnsutils`.
Juice the information out!
Only `format()` once. Don't create the debug message, just log it.
Accept all arguments coming from the user state
Merge pull request #4563 from UtahDave/fix_win_useradd

Accept all arguments coming from the user state
Add empty gid to user.info on Windows