Fix sending lists of data inside the argument list

Since we can't do varargs in Erlang, we use lists:
  send(Cxn, Key, [Value1, Value2, Value3])
But sometimes we want to be lazy and just do:
  send(Cxn, Key, "set a value")

This patch allows both cases to co-exist.  Instead of (as
previously) crashing, we convert the inner values to
binaries then return the converted list.  At the end, the deep
list of binaries is flattened to perform redis protocol
calculations and construction.

src/erldis.erl

@@ -346,11 +346,12 @@ exec(Client, Fun) ->
 multibulk_cmd(Args) when is_binary(Args) ->
   multibulk_cmd([Args]);
 multibulk_cmd(Args) when is_list(Args) ->
-  TotalLength = length(Args),
-
+  ConvertedArgs = lists:flatten([erldis_binaries:to_binary(B) || B <- Args]),
+  TotalLength = length(ConvertedArgs),
+
   ArgCount = [<<"*">>, ?i2l(TotalLength), <<"\r\n">>],
-  ArgBin = [[<<"$">>, ?i2l(iolist_size(A)), <<"\r\n">>, 
-             A, <<"\r\n">>] || A <- [erldis_binaries:to_binary(B) || B <- Args]],
+  ArgBin = [[<<"$">>, ?i2l(iolist_size(A)), <<"\r\n">>, A, <<"\r\n">>]
+            || A <- ConvertedArgs],
 
   [ArgCount, ArgBin].
 

src/erldis_binaries.erl

@@ -3,6 +3,9 @@
 -export([to_binary/1]).
 
 to_binary(X) when is_binary(X)  -> X;
-to_binary(X) when is_list(X)    -> list_to_binary(X);
+% Basic determination of a char list: "abc"
+to_binary(X) when is_list(X) andalso is_integer(hd(X)) -> list_to_binary(X);
+% Basic determination of a list of stuff: [abc, def, <<"other">>, 12]
+to_binary(X) when is_list(X)    -> [to_binary(A) || A <- X];
 to_binary(X) when is_atom(X)    -> list_to_binary(atom_to_list(X));
 to_binary(X) when is_integer(X) -> list_to_binary(integer_to_list(X)).