Don't set npm_package_ensure

Using repo_url_suffix implies nodesource packaging, whose nodejs
package bundles the npm executable rather than having it in a
separate package. Attempting to set npm_package_ensure to present
results in dependency resolution conflict when the module attempts
to install the distro's npm package which conflicts with the nodejs
package being installed from nodesource. This is consistent with the
behavior described by
https://github.com/voxpupuli/puppet-nodejs#npm_package_ensure as
well.

Change-Id: I9516bf52c72609355748e6a521eef21020f75fe4

manifests/frontend.pp

@@ -11,7 +11,6 @@ class openstack_health::frontend(
   class { '::nodejs':
     legacy_debian_symlinks => true,
     repo_url_suffix        => 'node_0.12',
-    npm_package_ensure     => 'present',
   }
 
   package { 'node-gyp':