recurls: Support CONFIG verb

Allows to use backends not following typical HTTP VERBS.

src/recurls/recurls.py

@@ -35,6 +35,9 @@ class Recurls(object):
   def get(self, url, **kwargs):
     return self.request('GET', url, **kwargs)
 
+  def config(self, url, **kwargs):
+    return self.request('CONFIG', url, **kwargs)
+
   def put(self, url, **kwargs):
     return self.request('PUT', url, **kwargs)