Namecoin error logging changes

- namecoin connection errors have now severity "info" instead of
  "error", because it just confuses peopel who don't have namecoin
  configured
- partially addresses #893

src/namecoin.py

@@ -158,7 +158,7 @@ class namecoinConnection (object):
                 assert False
 
         except Exception:
-            logger.exception("Namecoin connection test failure")
+            logger.info("Namecoin connection test failure")
             return ('failed', "The connection to namecoin failed.")
 
     # Helper routine that actually performs an JSON RPC call.
@@ -208,9 +208,9 @@ class namecoinConnection (object):
                 if resp.status != 200:
                     raise Exception ("Namecoin returned status %i: %s", resp.status, resp.reason)
             except:
-                logger.error("HTTP receive error")
+                logger.info("HTTP receive error")
         except:
-            logger.error("HTTP connection error", exc_info=True)
+            logger.info("HTTP connection error")
 
         return result