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.
Update README and services template
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
Merge pull request #148 from srodrig0209/cook2630

[COOK-2630] Update README and services template
add attribute allowed_hosts; if present, client recipe will use the value specified instead of searching for an IP
concatenate the allowed_hosts attribute to the list of monitored hosts if it is defined after the search so that both can be leveraged at once
change a spec so that it ensures a search with no results does not raise an error
only allow arrays of strings for allowed_hosts
set default for allowed_hosts attribute to nil
Merge branch 'COOK-2460'
remove Gemfile.lock entirely
add the "cookbook" option in the definition "nagios_conf"
Merge branch 'COOK-2988' of github.com:criteo-cookbooks/nagios into COOK-2669

Conflicts:
	attributes/client.rb