cleaned up issues with Daniel's code

There were a lot of style things and a misunderstanding of the protocol
between the cape and the BBB.
diff --git a/bbb_cape/src/cape/data_struct.h b/bbb_cape/src/cape/data_struct.h
index 95992b9..797648f 100644
--- a/bbb_cape/src/cape/data_struct.h
+++ b/bbb_cape/src/cape/data_struct.h
@@ -60,6 +60,7 @@
 
 // The number of bytes that we actually send (so it stays consistent) (including
 // the byte-stuffing overhead and the CRC on the end).
+// This will always be a multiple of 4.
 #define DATA_STRUCT_SEND_SIZE 200
 
 #ifdef __cplusplus