Fix metapackage linking on Ubuntu 14.04

It's optional (and enabled by default) to manage dependencies of the
module needed during deployment with `package` declarations (see
`build_deps` and `::nodejs::pkgs`).

However the `rubygems` package which explicitly ensures that the `gem`
provider is functional on each host is a metapackage that will be
replaced by `ruby`. This "linking" doesn't work on Ubuntu 14.04 LTS
which is still supported (please refer to the forum for further
reference: https://askubuntu.com/questions/613074/package-rubygems-has-no-installation-candidate).

Now each OS with `$::osfamily == 'Debian'` uses `rubygems-integration`
to fix the broken linking.

Fixes #181

manifests/instance/pkgs.pp

@@ -16,7 +16,12 @@
     warning('nodejs::instance::pkgs is private!')
   }
 
-  ensure_packages(['tar', 'wget', 'ruby', 'rubygems'])
+  $rubygems = $::osfamily ? {
+    'Debian' => 'rubygems-integration',
+    default  => 'rubygems'
+  }
+
+  ensure_packages(['tar', 'wget', 'ruby', $rubygems])
   ensure_packages(['semver'], {
     provider => gem,
     require  => Package['ruby'],

spec/classes/nodejs_instance_pkgs_spec.rb

@@ -2,10 +2,21 @@
 
 describe 'nodejs::instance::pkgs', :type => :class do
   let(:title) { 'nodejs::instance::pkgs' }
+  let(:facts) {{
+    :osfamily => 'Debian'
+  }}
 
   describe 'module dependency management' do
     it { should contain_package('wget') }
     it { should contain_package('tar') }
+    it { should contain_package('rubygems-integration') }
+  end
+
+  describe 'redhat OS' do
+    let(:facts) {{
+      :osfamily => 'RedHat',
+    }}
+    it { should contain_package('rubygems') }
   end
 
   describe 'includes compiler-related dependencies' do