simplify schema.rb reset in upgrade guides

Cleanup MySQL database

Addresses changes made to installation guide and config files but never
applied in update process. Relevant changes to installation guide and
config files were made in
gitlabhq@cbb5b00,
gitlabhq@498a4e6,
gitlabhq@c33d5e1,
gitlabhq@485162e#diff-e1059d0fa0437ffad94facff86210603,
gitlabhq@72e2fe2#diff-d1b4ff7de834bae6008dd49550413a6f,
gitlabhq@5163a8f#diff-e1059d0fa0437ffad94facff86210603,
gitlabhq@993af5d#diff-e1059d0fa0437ffad94facff86210603,
&
gitlabhq@d3f5a0c.

Fix ambiguous sha problem with mentioned commit

Before: write in database only 6 chars of commit sha. This cause to `Ambiguous SHA1 prefix` exception.

- [x] write full commit sha in db.
- [x] Standardise usage of sha truncation: 8 characters everywhere.
- [x] prevent exception when ambiguous sha requested in markdown

Fixes #1644

See merge request !1171

Bug with apostrophe when at mentioning users

This fixes the situation where mentioning user with apostrophe at the end causes a link to issue 39 if the project has that issue, so `@marin` would look like `@marin's`.

Fixes #1034

See merge request !1165

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

Enabling markdown pipelines from gitlab

Define which markdown pipelines are used in GitLab from application instead from gem.

See merge request !1164

improve wording on protected branches page

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>

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

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

Ssl ciphers update

See merge request !1168

This reverts commit c41e5f50.

Remove unused method

Annotate

See merge request !1167

Snippets need to be either public/internal/private

See merge request !1162

Bump grit

Fixes gitlab/grit#7

See merge request !1166

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

Ruby version

I set it to the latest ruby stable version, that in my experience works without issues.

/cc @jw

See merge request !1163