Fix syntax if nagios_hostgroups data bag based search returns nothing

Don't write out "members empty" if nothing comes back from the search.
Instead write out a host group with nothing, which is actually correct.
 Also remove an empty line so that there is a single empty line between
each host group definition.
Install Nagios 3.5.0 when installing from source

Bug fixes:

    Fixed bug #403: The "configuration" page of the webui doesn't use
entity encoding when displaying the "command expansion" item (Eric
Stanley, Phil Randal)
    Fixed bug #424: Nagios Core 3.4.4 seg fault (core dump) on restart
after removing config for running service (Eric Stanley)
    Updated CGI utility functions to support UTF-8 characters (Eric
Stanley)
    Fixed bug where selecting Command Expansion from Configuration CGI
page would display commands instead (Eric Stanley)
    Fixed bug #369: status.cgi crashes with segfault when there are
german ulauts (äöüß) in the hostname or the servicename (Eric Stanley)
    Fixed bug #418: Scheduled Downtime Notifications Resent On Nagios
Restart/reload (Eric Stanley)
allowing nagios servers to NRPE check each other.
PR feedback
Merge pull request #145 from tas50/COOK-2612

COOK-2612: Fix syntax if nagios_hostgroups data bag based search returns nothing
Merge pull request #146 from tas50/COOK-2613

COOK-2613: Install Nagios 3.5.0 when installing from source
Merge pull request #147 from maplebed/COOK-2642

allowing nagios servers to NRPE check each other.
release v4.1.0
increment version for development
If the server is behind a NAT, we need to accept requests from its gateway

For example, if the server is a virtual machine and that we want to
monitor physical servers.