Let's update Copyright notice to 2019.

rultor released this 15 May 13:32

· 221 commits to master since this release

See #116, release log:

40f6f82 by @yegor256: #116 nokogiri up
a8151f0 by @yegor256: #117 year up
f14af43 by @yegor256: #117 simplified

Released by Rultor 1.68.3, see build log

Assets 2