Update some copyright dates, somewhat belatedly.

LICENSE

@@ -1,4 +1,4 @@
-"iperf, Copyright (c) 2014-2017, The Regents of the University of California,
+"iperf, Copyright (c) 2014-2018, The Regents of the University of California,
 through Lawrence Berkeley National Laboratory (subject to receipt of any 
 required approvals from the U.S. Dept. of Energy).  All rights reserved."
 

README.md

@@ -163,7 +163,7 @@ responsibility for the content of these pages.
 Copyright
 ---------
 
-iperf, Copyright (c) 2014-2017, The Regents of the University of
+iperf, Copyright (c) 2014-2018, The Regents of the University of
 California, through Lawrence Berkeley National Laboratory (subject
 to receipt of any required approvals from the U.S. Dept. of
 Energy).  All rights reserved.