Add pbkdf2 dependencies and fix the building errors

rebar.config

@@ -1,4 +1,4 @@
 {deps, [
-{gproc,".*",{git,"https://github.com/uwiger/gproc",""}},{lager,".*",{git,"https://github.com/basho/lager","master"}},{esockd,".*",{git,"https://github.com/emqtt/esockd","master"}},{mochiweb,".*",{git,"https://github.com/emqtt/mochiweb",""}},{lager_syslog,".*",{git,"https://github.com/basho/lager_syslog",""}}
+{gproc,".*",{git,"https://github.com/uwiger/gproc",""}},{lager,".*",{git,"https://github.com/basho/lager","master"}},{esockd,".*",{git,"https://github.com/emqtt/esockd","master"}},{mochiweb,".*",{git,"https://github.com/emqtt/mochiweb",""}},{lager_syslog,".*",{git,"https://github.com/basho/lager_syslog",""}},{pbkdf2,".*",{git,"https://github.com/comtihon/erlang-pbkdf2.git","2.0.0"}}
 ]}.
 {erl_opts, [{parse_transform,lager_transform}]}.

src/emqttd_client.erl

@@ -252,7 +252,7 @@ handle_info({keepalive, start, Interval}, State = #client_state{connection = Con
                     {error, Error}              -> {error, Error}
                 end
              end,
-    case emqttd_keepalive:start(Statfun, Interval, {keepalive, check}) of
+    case emqttd_keepalive:start(StatFun, Interval, {keepalive, check}) of
         {ok, KeepAlive} ->
             {noreply, State#client_state{keepalive = KeepAlive}, hibernate};
         {error, Error} ->

src/emqttd_ws_client.erl

@@ -202,7 +202,7 @@ handle_info({keepalive, start, Interval}, State = #wsclient_state{connection = C
         {ok, KeepAlive} ->
             {noreply, State#wsclient_state{keepalive = KeepAlive}, hibernate};
         {error, Error} ->
-            ?LOG(warning, "Keepalive error - ~p", [Error], State),
+            ?WSLOG(warning, "Keepalive error - ~p", [Error], State),
             shutdown(Error, State)
     end;