email errors to admin

See #46, release log:

• dd214db by @yegor256: #46 rultor config
• 248f2f9 by @yegor256: #46 deploy
• 73130f2 by @yegor256: #46 Gemfile.lock into .gitigno...
• e2fd31d by @yegor256: #46 Gemfile.lock removed
• 0142c9c by @yegor256: #46 always email to admin@0pdd...
• b13df9b by @yegor256: #44 Gemfile.lock removed

Released by Rultor 1.62.2, see build log