Improve test env

* Replace big gitlabhq repo with small one (https://gitlab.com/gitlab-org/gitlab-test)
* dont stub gitlab-shell calls

Advantages:

* test gitlab-shell install during tests
* test integration with gitlab-shell features (fork, change default branch etc)
* don't store archive with test repo inside gitlab
* less stubs - easier to write/read tests

During this refactoring __next issues are be fixed__:

* satellite error if gitlab_shell path is relative
* project rename repo -> 500 error
* fixed wrong diff for MR `download plain diff`
* fixed bug when gfm ignores `@ref` variable during link parsing

Fixes #1451

See merge request !1005

Signed-off-by: Dmitriy Zaporozhets <dmitriy.zaporozhets@gmail.com>

Signed-off-by: Dmitriy Zaporozhets <dmitriy.zaporozhets@gmail.com>

make bullet punctuation on protected branches page consistent

Fix spelling errors in documentation

Further changes

add application check commands to 5.0 to 5.1 upgrade guide

Make file edit error message less specific

See merge request !1007

The truth is that at the point where there error message is written we
can only guess what went wrong.

Signed-off-by: Dmitriy Zaporozhets <dmitriy.zaporozhets@gmail.com>

Signed-off-by: Dmitriy Zaporozhets <dmitriy.zaporozhets@gmail.com>

Signed-off-by: Dmitriy Zaporozhets <dmitriy.zaporozhets@gmail.com>

Signed-off-by: Dmitriy Zaporozhets <dmitriy.zaporozhets@gmail.com>

Signed-off-by: Dmitriy Zaporozhets <dmitriy.zaporozhets@gmail.com>

Simplify ssl setup

/cc @dzaporozhets

Fixes #1409

See merge request !1006

Add command to remove GitLab user

add command to start rails console

Self signed SSL cert not supported until 5.1

[DOC] Mention the @all GFM reference in documentation

[DOC] Replace invalid emojis

Update 6.9-to-7.0.md

Signed-off-by: Dmitriy Zaporozhets <dmitriy.zaporozhets@gmail.com>

Signed-off-by: Dmitriy Zaporozhets <dmitriy.zaporozhets@gmail.com>

Signed-off-by: Dmitriy Zaporozhets <dmitriy.zaporozhets@gmail.com>

Signed-off-by: Dmitriy Zaporozhets <dmitriy.zaporozhets@gmail.com>

Signed-off-by: Dmitriy Zaporozhets <dmitriy.zaporozhets@gmail.com>

Signed-off-by: Dmitriy Zaporozhets <dmitriy.zaporozhets@gmail.com>