Punycode URI normalization (#2370)

* Fix #2119 - Whenever about to send a HTTP request, normalize the URI

* Add test for IDN request in FetchLinkCardService

* Perform IDN normalization on domains before they are stored in the DB

app/lib/tag_manager.rb

@@ -64,6 +64,12 @@ class TagManager
     domain.nil? || domain.gsub(/[\/]/, '').casecmp(Rails.configuration.x.local_domain).zero?
   end
 
+  def normalize_domain(domain)
+    uri = Addressable::URI.new
+    uri.host = domain
+    uri.normalize.host
+  end
+
   def same_acct?(canonical, needle)
     return true if canonical.casecmp(needle).zero?
     username, domain = needle.split('@')
@@ -71,7 +77,7 @@ class TagManager
   end
 
   def local_url?(url)
-    uri    = Addressable::URI.parse(url)
+    uri    = Addressable::URI.parse(url).normalize
     domain = uri.host + (uri.port ? ":#{uri.port}" : '')
     TagManager.instance.local_domain?(domain)
   end