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

This reverts commit 17835f09.