This was the only thing using the `sdoc` gem, which was blocking another
gem from updating.

This adds the 2016 emoji as well as support for using SVG images instead of PNGs.

It also fixes a number of incorrectly categorized emoji and other minor issues.

Upgrade Rake task for Gemojione 3.0.0 and generate sprites.

Upgrade aliases.json by pulling down index.json from the gemojione repository and running the generate_aliases.rb file.

Changelog: https://github.com/jonathanwiesel/gemojione/blob/master/CHANGELOG.md#v301-2016-07-16

For the specific emoji added to the Unicode standard, see: http://emojione.com/releases/2.2.4/

Huge kudos to Jonathan Wiesel (@jonathanwiesel) for his work on the gemojione gem!

Fixes gitlab-org/gitlab-ce#14794 gitlab-com/performance#13

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Using db:reset ensures existing tables are first dropped. This in turn
ensures that we can drop tables regardless of any foreign key
constraints. While CE currently doesn't have any foreign keys EE defines
the following relation:

    remote_mirrors.project_id -> projects.id

MySQL will complain whenever you try to drop the "projects" table first
even when using "DROP TABLE ... CASCADE".

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