Modified the year in the license

I edited the license.
4 jobs from 87-migrate-pk in 1 minute and 17 seconds (queued for 2 seconds)
Status Job ID Name Coverage
  Test
passed #1719
Go-py2.7

00:01:15

passed #1720
Go-py3.4

00:01:16

passed #1721
Go-py3.5

00:01:16

passed #1722
Go-py3.6

00:01:17

56.0%