chore(deps) bump lua-cassandra to 1.2.1

This ensures we update the Nginx time between schema consensus timeout
checks and also adds the ability to manually add and remove C* peers.

thibaultcha/lua-cassandra@1.1.1...1.2.1

kong-0.10.1-0.rockspec

@@ -20,7 +20,7 @@ dependencies = {
   "multipart == 0.5",
   "version == 0.2",
   "lapis == 1.5.1",
-  "lua-cassandra == 1.1.1",
+  "lua-cassandra == 1.2.1",
   "pgmoon-mashape == 2.0.1",
   "luatz == 0.3",
   "lua_system_constants == 0.1.1",