Enable cassim by default

COUCHDB-2879
diff --git a/src/cassim.erl b/src/cassim.erl
index 65d942c..aeebb2a 100644
--- a/src/cassim.erl
+++ b/src/cassim.erl
@@ -51,7 +51,7 @@
 
 
 is_enabled() ->
-    config:get_boolean("cassim", "enable", false).
+    config:get_boolean("cassim", "enable", true).
 
 
 metadata_db_exists() ->