Specify provider so it doesn't try to use an incorrect provider

[dandunckelman]

Redoing #43, since I had deleted the original repo.

When I first setup this class on a Windows 2012 host, it failed stating that it needed chocolatey to install the package:

Failed to apply catalog:
  Parameter provider failed on Package[New Relic Server Monitor]:
    Invalid package provider 'chocolatey' at /etc/puppet/environments/production/modules/newrelic/manifests/server/windows.pp:90
    Wrapped exception: Invalid package provider 'chocolatey'

To get around this, I specify the windows provider, which is all that this PR contains.

Anything I can do to get this merged? Or any reason it's ignored?

In my environment, chocolatey is the default package provider on Windows hosts, which I don't want in this case. It seems reasonable to specify the proper provider. Or is there a workaround I can apply?

[dandunckelman]

Any way to get the travis builds to retry?