integrate author check into travis

doc/generate_authors.sh

@@ -0,0 +1,14 @@
+#!/bin/sh
+
+GENLIST=$(git shortlog -s -n | cut -f2 | sort)
+AUTHORSFILE="$(dirname $0)/../AUTHORS"
+TEMPAUTHORSFILE="/tmp/python-escpos-authorsfile"
+
+if [ "$#" -eq 1 ]
+    then
+        echo "$GENLIST">$TEMPAUTHORSFILE
+        diff -q --from-file $AUTHORSFILE $TEMPAUTHORSFILE
+    else
+	echo "$GENLIST">$AUTHORSFILE
+fi
+