nginx version fact compatibility with Facter 1.7

lib/facter/nginx_version.rb

@@ -1,7 +1,7 @@
 Facter.add(:nginx_version) do
   setcode do
-    if Facter::Core::Execution.which('nginx')
-      nginx_version = Facter::Core::Execution.execute('nginx -v 2>&1')
+    if Facter::Util::Resolution.which('nginx')
+      nginx_version = Facter::Util::Resolution.exec('nginx -v 2>&1')
       %r{^nginx version: nginx\/([\w\.]+)}.match(nginx_version)[1]
     end
   end

spec/unit/nginx_version_spec.rb

@@ -8,8 +8,8 @@ describe Facter::Util::Fact do
   describe "nginx_version" do
     context 'with value' do
       before :each do
-        Facter::Core::Execution.stubs(:which).with('nginx').returns(true)
-        Facter::Core::Execution.stubs(:execute).with('nginx -v 2>&1').returns('nginx version: nginx/1.8.1')
+        Facter::Util::Resolution.stubs(:which).with('nginx').returns(true)
+        Facter::Util::Resolution.stubs(:exec).with('nginx -v 2>&1').returns('nginx version: nginx/1.8.1')
       end
       it {
         expect(Facter.fact(:nginx_version).value).to eq('1.8.1')