Created waiteject.sh to wait on USB storage eject. (#374)

payloads/extensions/waiteject.sh

@@ -0,0 +1,14 @@
+#!/bin/bash
+#
+# WAITEJECT v1 by kamotswind (https://github.com/kamotswind)
+# Blocks the payload from continuing until the USB storage is ejected from the host
+# Usage: WAITEJECT
+
+function WAITEJECT() {
+	until [ ! -z "`dmesg | grep \"usb close backing file\"`" ]
+	do
+		sleep 1
+	done
+}
+
+export -f WAITEJECT