Add version 2.0 and detect for yz admin

Author: coderoshi

riak/transports/feature_detect.py

@@ -24,7 +24,8 @@
     1: LooseVersion("1.0.0"),
     1.1: LooseVersion("1.1.0"),
     1.2: LooseVersion("1.2.0"),
-    1.4: LooseVersion("1.4.0")
+    1.4: LooseVersion("1.4.0"),
+    2.0: LooseVersion("2.0.0")
 }
 
 
@@ -71,7 +72,7 @@ def pb_search_admin(self):
 
         :rtype: bool
         """
-        return self.server_version >= versions[1.4]
+        return self.server_version >= versions[2.0]
 
     def pb_search(self):
         """