VERSION 0.6.13: small bug fix, UI work

This is just a small bug fix and some UI work. Version bumps will be
coming faster too to test auto-update.

version.h

@@ -41,6 +41,6 @@
 /**
  * Revision
  */
-#define ZEROTIER_ONE_VERSION_REVISION 12
+#define ZEROTIER_ONE_VERSION_REVISION 13
 
 #endif