Facebook removed the API and facebook integration is broken now, so lets
remove it.

closes #7874

Otherwise camo crashes with:
TypeError [ERR_UNESCAPED_CHARACTERS]: Request path contains unescaped characters

closes #7871

/ was missing in the profile entity $ref

closes #7835

LinksController redirects requests for provided diaspora:// links to
respective entities urls.

This adds a new dependency (`libidn11-dev` on debian, I'm not sure about
other distros).

This reverts commit 070e4caa.

Fixes #7695.

closes #7777

This feature only worked on the same pod and was more confusing than
useful.

closes #7718

This can be used in later diaspora versions to order the profile updates
so we don't overwrite a newer profile with older data.

This is to let the author of the post know, that this pod is interested
in updates about this post.

The sending user is only used to verify that the participation was sent
from this pod, but lets use an admin/podmin account if available.

closes #7708

fixes #7701
closes #7702

closes #7683

Fixes #7651

closes #7652

[ci skip]

closes #7646

closes #7641

closes #7639

This uses a lot of memory for big accounts. Also it doesn't make much
sense to rollback everything when something fails, it's better to delete
everything we can.

- Removed posts and non contacts from other's data
- Collections are exported in batches to lower memory footprint
- In base exporters create User object instead of keeping instance because it caches all associations

closes #7627

closes #7595

closes #7605

This was in all stack traces, which confused people ...

We currently only support IE11, so the version check was already old
again ...

When we break old browser versions, we don't check that for other
browsers. So older IE browser just break, like very other older browser
too.

closes #7557

closes #7571

This commit introduces support for AccountMigration federation message
receive. It covers the cases when the new home pod for a user is remote
respective to the recepient pod of the message. It also allows to initiate
migration locally by a podmin from the rails console. This will give the
pods a possibility to understand the account migration event on the
federation level and thus future version which will implement migration
will be backward compatible with the pods starting from this commit.

Also remove `disconnect_contacts` methods, because contacts are already
removed with aspects memberships in `before_destroy`.

Although this is contrary to rails best-practises, we cannot provide a schema.rb that works for both MySQL and PostgreSQL, so we have no choice. Our migrations are maintained, so it should always be possible to get back to a "clean" database schema anyway.