Release 0.3

Notable changes:
 * A new binary, quark-test(8) for testing the suite.
 * An initramfs.gz target including init and infrastructure to run quark-test
   statically built on any kernel via qemu.
 * Quark now knows about 4 namespaces (uts,ipc,mnt,net) and they're included in
   quark_process{}.
 * Fixed pgid in RHEL8 since the enum value changes, also fixed upstream
   elastic/ebpf.

quark.h

@@ -5,7 +5,7 @@
 #define _QUARK_H_
 
 /* Version is shared between library and utilities */
-#define QUARK_VERSION "0.3a"
+#define QUARK_VERSION "0.3"
 
 /* Misc types */
 #include <stdio.h>