Update the source code URI (#1394)

Update the source code URI so that rubygems references the repository
that the code was moved to instead of from before when it was hosted
under the original author's personal org.

vagrant-libvirt.gemspec

@@ -9,6 +9,9 @@ Gem::Specification.new do |s|
   s.description   = %q{libvirt provider for Vagrant.}
   s.summary       = %q{libvirt provider for Vagrant.}
   s.homepage      = VagrantPlugins::ProviderLibvirt::HOMEPAGE
+  s.metadata      = {
+    "source_code_uri" => VagrantPlugins::ProviderLibvirt::HOMEPAGE,
+  }
 
   s.files         = Dir.glob("{lib,locales}/**/*") + %w(LICENSE README.md)
   s.executables   = Dir.glob("bin/*.*").map{ |f| File.basename(f) }