Add support for MaxStartups and MaxSessions in sshd_config

MaxStartups and MaxSessions control how many connections can be made to a ssh server.
Corrected faulty commented value for MaxStartups.
Improve validation of sshd_config_maxstartups and add spec tests
Support Ruby v2.1.0
Merge pull request #99 from ghoneycutt/maxstartups_and_maxsessions

Maxstartups and maxsessions
Release v3.23.0 - Support MaxStartups and MaxSessions in sshd_config
Support versions of Puppet Enterprise greater than 3.3
Merge pull request #100 from ghoneycutt/support_newer_versions_of_pe

Support versions of Puppet Enterprise greater than 3.3
Support Puppet Enterprise > 3.2 and < 4
Manage the ssh_known_hosts file when ssh_key_import is used
Always manage ssh_known_hosts and add spec tests