fix connection string parser to parse integer value from db

Author: artemeff

lib/exredis/connection_string.ex

@@ -16,7 +16,7 @@ defmodule Exredis.ConnectionString do
 
   defp parse_db(nil), do: 0
   defp parse_db(path) do
-    path |> String.split("/") |> Enum.at(1)
+    path |> String.split("/") |> Enum.at(1) |> String.to_integer
   end
 
   defp parse_password(nil), do: ''

test/connection_string_test.exs

@@ -15,7 +15,7 @@ defmodule ConnectionStringTest do
     assert config.host == 'host'
     assert config.port == 1234
     assert config.password == 'password'
-    assert config.db == "10"
+    assert config.db == 10
   end
 
   test "parsing a connection string without user" do