Proper use of null for jiffy-style encoding/decoding.

Author: Andrew Kirilenko

src/msgpack_packer.erl

@@ -34,8 +34,10 @@ pack(F, _) when is_float(F) ->
     pack_double(F);
 pack(null, _Opt = ?OPTION{interface=jsx}) ->
     << 16#C0:8 >>;
+pack(null, _Opt = ?OPTION{interface=jiffy}) ->
+    << 16#C0:8 >>;
 pack(nil, _Opt = ?OPTION{interface=Interface}) 
-  when Interface =/= jsx ->
+  when Interface =/= jsx andalso Interface =/= jiffy ->
     << 16#C0:8 >>;
 pack(false, _) ->
     << 16#C2:8 >>;

src/msgpack_unpacker.erl

@@ -35,6 +35,8 @@
 %% ATOMS
 unpack_stream(<<16#C0, Rest/binary>>, _Opt = ?OPTION{interface=jsx}) ->
     {null, Rest};
+unpack_stream(<<16#C0, Rest/binary>>, _Opt = ?OPTION{interface=jiffy}) ->
+    {null, Rest};
 unpack_stream(<<16#C0, Rest/binary>>, _) ->
     {nil, Rest};
 unpack_stream(<<16#C2, Rest/binary>>, _) ->