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.
Add user wildcard matching for external auth
Include the filesystem cleanup options group into the parser.
Merge pull request #4547 from sfdc-kho/develop

Add user wildcard matching for external auth
Merge pull request #4548 from s0undt3ch/develop

Include the filesystem cleanup options group into the parser.
Fix for #4514

Cleaning up warning/error messages for issue #4514.  There are now
log messages when either aptsources.sourceslist or
softwareproperties.ppa fail to import.  There are also clearer
log warnings when trying to use functions from either.
Allow for the main session key to be updated hot
Add dropfile function to utils
Move to salt.crypt
Fix #4520

Call for a refresh on the publish session key when removing keys
and rejecting keys forcing rejected minions to re-auth
Pass in the cachedir to dropfile
Doh! Default the mtime to an integer
Rotate the publish crypt session daily
Formatting Fix for #4514

Formatting fix on warning message(s) when python-software-properties
is unavailable.
Fix ssh-auth.absent to search for just the key; Fixes #4170

Previously was searching for the whole line, and ssh.rm_auth_key and
ssh.check_key were both expecting just the key part.
Set result=None not return=None for test=True