Modified the year in the license

I edited the license.
4 jobs for 137-license_update in 1 minute and 33 seconds (queued for 2 seconds)
Status Name Job ID Coverage
  Test
passed Go-py2.7 #1691

00:01:30

passed Go-py3.4 #1692

00:01:26

passed Go-py3.5 #1693

00:01:32

passed Go-py3.6 #1694

00:01:32

56.0%