Additions to RemoveDuplicateRepositories migration

Update refinements: 5.0.2 → 5.1.0 (minor)

[frontend] Fix structure.sql

One of the recent changes (b288c877) added a migration
version to the db/strucutre.sql that does not exist.

Corrected commit message on PR for issue #4442

[ci] Add rspec-retry

[webui][api] Fix ChangeRepositoriesRemoteProjectNameToNotNull migration

Update mysql2: 0.4.10 → 0.5.0 (minor)

Upgrade data_migrate: 3.4.0 → 3.5.0 (minor)

Update rails: 5.1.5 → 5.1.6 (patch)

Replaced broken contact link in Contributing.md to fix issue #4442

[frontend] Drop test for fuzzy time

The migration ChangeRepositoriesRemoteProjectNameToNotNull changes the default
of remote_project_name to '' instead of NULL.
This was necessary in order to make the combination of remote_project_name,
db_project_id and name unique because MySQL does not consider rows with same column content
but one NULL value as equal. The migration back then was removing duplicates, however,
it also migrated repositories which are associated with remote projects. These
repositories do not need to get migrated as they're anyway unique
(there can not be a NULL value for these repositories).

This commit splits this migration in a schema and a data migration and introduces specs
for the data migration.
The data migration gets changed to NOT migrate repositories of a remote project.
If there is duplicate repository found, we simply destroy it as the data is already inconsistent
and it is not possible to do a full migration.

Fix #4761.

[backend] enable EFI binaries signing for Debian packages

Extract authentication actions from `UserController`

this is necessary when Mysql DDE statements (create/drop/truncate table) are used
because these are not supported by transaction strategy otherwise it will raise an
'ActiveRecord::StatementInvalid: Mysql2::Error: SAVEPOINT active_record_1 does not exist: ROLLBACK TO SAVEPOINT active_record_1'
exception.

https://stackoverflow.com/questions/13161394/activerecord-error-savepoint-active-record-1-does-not-exist

This test is not adding much value since it's just ensure that the
result of a rails helper (*.ago) is properly shown.
It's also flickering quite often and causes our test suite to fail.

So let's drop it.

Because it has not been tested yet.

To make it slightly more readable

It did not make sense to manage login/logout actions from
`UserControllers`, reason why they were moved to its own controller.

Note that this change also implies modifications in routes

  - GET  user_login_path    -> GET    session_new_path
  - POST user_do_login_path -> POST   session_create_path
  - POST user_logout_path   -> DELETE session_destroy_path

Just like for RPMs, if a Debian package build creates $pkg.cpio.rsasign
trigger a signd signature and a rebuild (look for .dsc other than .spec
for the followup build).

The packages to actually do the sign&repack for kernel, shim and grub
can be found:

https://github.com/bluca/linux-signed/tree/obs
https://github.com/bluca/shim-signed/tree/obs
https://github.com/bluca/grub2-signed/tree/obs
https://build.opensuse.org/project/show/home:bluca:debian_secure_boot

We now always allow stripping of the first component if the
first entry is a directory.

That way people learn how to access their containers.

Adding an optional pushserver config, for registries having an own push interface

[frontend] Temporarely skip test

This test currently blocks our package builds because it's constantly
failing there (We run all our tests within the rpm package builds again).

[frontend] Refactor request validation test

[frontend] Sanitize patchinfo input before saving it

Reduce cassette size

If the request creator is not confirmed, he might get might not get
logged in. Therefor it's better to user some other request related
validation.

[frontend] Fix fuzzy time, part II

Remove leading / trailing whitespaces from rating and category.

Fixes #4662

Refactor js for patchinfos