Added Contra keyboard support (#2501)

* Added Contra keyboard support

The configuration came from a source distribution of the firmware on the
Contra's official website.

I have also included a simple MIDI keymap. (And it works!)

* Changes to Contra config and README

* Readme has been changed as requested by jackhumbert
* Config has been changed to add the Cartel and Contra names to
  the USB configuration.

keyboards/contra/keymaps/dana/config.h

@@ -0,0 +1,30 @@
+/*
+Copyright 2012 Jun Wako <wakojun@gmail.com>
+
+This program is free software: you can redistribute it and/or modify
+it under the terms of the GNU General Public License as published by
+the Free Software Foundation, either version 2 of the License, or
+(at your option) any later version.
+
+This program is distributed in the hope that it will be useful,
+but WITHOUT ANY WARRANTY; without even the implied warranty of
+MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+GNU General Public License for more details.
+
+You should have received a copy of the GNU General Public License
+along with this program.  If not, see <http://www.gnu.org/licenses/>.
+*/
+
+#ifndef CONFIG_USER_H
+#define CONFIG_USER_H
+
+#include "../../config.h"
+
+
+#undef TAPPING_TERM
+#define TAPPING_TERM 190
+
+#define MUSIC_MASK (keycode != KC_NO)
+#define MIDI_ADVANCED
+
+#endif