config/site_config.yml.example: Update.
config/environments/development.rb: Add setting for mail.
config/environments/development.rb: Fix typo.
Generate ContactMailer.
app/mailers/contact_mailer.rb: Update.
Generae contact model.
db/schema.rb: Update
Generate contacts controller.
config/routes.rb: Routes for contact controller.
Contact mail is avalable.
Fix typo.
app/views/contacts/new.html.erb: arrange field size.
Enable/disable mail contact.
Merge feature-contact-mail.