VERSION 0.9.3: unreleased update with some fixes for Pi users

This version is being tagged and bagged, despite the fact that it's not
going to be released and won't be merged into master until 1.0.0 is ready.

It contains several Linux build fixes, a fix for a unix domain socket resource
leak, and build fixes for the Raspberry Pi.

version.h

@@ -41,6 +41,6 @@
 /**
  * Revision
  */
-#define ZEROTIER_ONE_VERSION_REVISION 2
+#define ZEROTIER_ONE_VERSION_REVISION 3
 
 #endif