Support for excluded_members property in Suse, Groupadd Gpasswd providers. Required unsupported error messages in Usermod provider.
Fix unit tests on group providers.

Note that one unit test case is removed for windows. The reason is that now we are guarding against adding existing members therefore we don't need to have the need to call set_members if add_members fails.
excluded_members support for groupmod provider.
exluded_members support in pw group provider.
Group spec fixed for CI.
Turn off functional group resource tests on MacOSX 10.6 due to caching issue on Etc.getgrnam() on certain boxes.
Fix specs on FreeBSD.
Fix specs on Solaris.
Fix the failing pw provider unit spec.
Merge pull request #1127 from opscode/CHEF-3297-part-2

Add excluded_members support to the rest of the group providers.