Fix Rubocop offenses.

- Set max method length to 10 lines in .rubocop.yml

- Refactor feedback mailer to shorten and rename `send_feedback` to `feedback_email`, and define the body of the email in app/views per Rails conventions.

- Shorten `display_homepage_links` by breaking it up into smaller methods.

- Refactor `info_box_key_corresponding_to_keyword` to use a guard clause.

- Remove unused method `looks_like_location`.

- Shorten `map_data` by defining the hash in a separate method.