some SQL syntax does not pass a table prefix (atom or string)

in the case of `create_name`, then third param may be a string or atom
prefix ... and in those cases should be treated as a prefix.

however syntax such as `VALUES (...)` will pass in the values list
information as the third tuple. this was causing spurious exceptions
to be thrown, rather than creating the correct table name

Author: aseigo

lib/ecto/adapters/sqlite3/connection.ex

@@ -1909,10 +1909,12 @@ defmodule Ecto.Adapters.SQLite3.Connection do
 
   defp quote_table(nil, name), do: quote_entity(name)
 
-  defp quote_table(_prefix, _name) do
+  defp quote_table(prefix, _name) when is_atom(prefix) or is_binary(prefix) do
     raise ArgumentError, "SQLite3 does not support table prefixes"
   end
 
+  defp quote_table(_, name), do: quote_entity(name)
+
   defp quote_entity(val) when is_atom(val) do
     quote_entity(Atom.to_string(val))
   end