adding the ability to test without VRPN

groundStation/src/backend/config.h

@@ -5,6 +5,7 @@
 #define DEFAULT_SOCKET "/var/run/ucart.socket"
 #define SOCKET_ENV "UCART_SOCKET"
 #define NOQUAD_ENV "UCART_NO_QUAD"
+#define NOVRPN_ENV "UCART_NO_VRPN"
 
 
 // If you are planning on using any of these env vars and you have