* Remove docker guide and put it in docs repo

* Move tasks to docs repo

* Move requirements to contributing doc

* Move advice about tagged releases to docs repo

* Move local domain and host config to docs repo

* Link to related tech

These were being skipped with `xit`, but we also just added the `unused` task to
the CI server, and it will be caught there. That seems good enough for this,
instead of requiring a full keys check on every local spec suite run.

* Add spec for media controller

* Add MediaAttachment.attached scope

* Simplify methods in media controller

Also improve efficiency of the mastodon:maintenance:add_static_avatars task

This change includes:

- Improve the spec coverage for incoming request to the webfinger action
- For requests without an accept header (ie, what a browser might look like),
  return a JSON response.
- For requests with an explicit format of xml or json, return that format.
- For requests using an accept header, return that format.

Also adds failing spec showing webfinger does not return xml, which covers the
issue described in: https://github.com/tootsuite/mastodon/issues/1983

* Add `required: true` option to foreign column

* Fixes NoMethodError

```
> Favourite.new.valid?
NoMethodError: undefined method `reblog?' for nil:NilClass
```

Sync text for toot form

Un utiliser mal expérimenté pourrait comprendre "retirer les erreurs".
Ici il s'agit d'une suppression pure et simple, pas une épuration/nettoyage.

clear would be translated "remove" instead of "cleaning" Cleaning can be unterstood "keep but clean"

This is necessary for boosting long posts on small screens - see this post for video: https://slime.global/@masklayer/102308

* Open sidekiq and pghero admin pages in new tabs

* Add missing comma

Without setting it, exim will reject the mail with a message like:
rejected EHLO from [10.20.0.1]: syntactically invalid argument(s): {}

* Allow using an SMTP server without authentication (e.g Postfix relay on the same host) by setting SMTP_LOGIN and SMTP_AUTH_METHOD to 'none'

* Add note in .env.production.sample about SMTP settings for servers where no auth is required

* Assume that SMTP_LOGIN and SMTP_PASSWORD will be blank if we set SMTP_AUTH_METHOD to none

* Add mask-icon (#1572)

* use updated svg logo for mask-icon

* update portuguese translation

added the missing fields and improved the translation

* pt translations fix

* improve last translation commit

* fix damn quotes

* add pt_br to index.jsx

* add pt-BR to import index.jsx

* add pt-BR to mastodon.jsx

* add pt-BR to settings_helper.rb

* add pt-BR to application.rb

* order alphabetically pt.jsx

* create pt-BR.jsx

* Create devise.pt-BR.yml

* language improvements to devise.pt.yml

* created doorkeeper.pt-BR.yml

* fixes to doorkeeper.pt.yml

* create pt-BR.yml

* improvements to pt.yml

* Create simple_form.pt-BR.yml

* Improvements to simple_form.pt.yml

* improvements to pt.yml

* Create hr.jsx

Start of Croatian translation

* Update settings_helper.rb

* Update application.rb

* Update application.rb

* Update index.jsx

* Remove overflow because it blocks scrolling on mobile safari.

* Add “-webkit-overflow-scrolling: touch;” to enable smooth scroll on mobile safari and other webkit browsers.

* Use radio buttons in user setting page.

Because select tags with long text are not fit in the width of mobile devices.

* Add flex property to fit labels to devise width.

* Change font size of select.

It causes auto zooming on mobile safari.

* Rubocop link for Sublime Text

* Fix rubocop links

* Link to gh issues page from contributing doc

Fix tiny typo, and added link to terms and conditions in confirmation email for Japanese. (#1975) (#1975)

* reduce unneed query when post without attachements.

This commit reduce following query:

```
 MediaAttachment Load (0.9ms)  SELECT "media_attachments".* FROM "media_attachments" WHERE "media_attachments"."status
_id" IS NULL AND 1=0 ORDER BY id asc
```

* fixed for more simple changes.

* Fix #1870 - Strip control characters out of strings in AtomSerializer

* Adjust according to comment by @alpaca-tc

* Add language detection via WhatLanguage and (de)serialization of it through Atom

* Fix default language in ProcessFeedService

* Re-add newline before 'react-rails' Gem to fix groupings

Fixes Code Climate issue