Travis CI builds failing

The Travis CI builds have been failing since example42@80a0867, which makes it difficult to verify that a pull request isn't really breaking anything.

The first build to fail was [build 59](https://travis-ci.org/example42/puppet-nagios/builds/14595011), which was failing because of ```Unknown function is_array```.  That problem seems to have been fixed by issue #31, which is a little strange because I would have expected it to have been fixed by issue #34.

In any case, the error being generated now is:

```
  1) nagios Test standard installation with monitoring should monitor the process
     Failure/Error: content = catalogue.resource('monitor::process', 'nagios_process').send(:parameters)[:enable]
     ArgumentError:
       wrong number of arguments (0 for 1)
     # ./spec/classes/nagios_spec.rb:29:in `block (3 levels) in <top (required)>'
```

All of the tests pass locally for me, so I'm not sure where the problem is.