Fix registration error info typo
Add .adoc file extension for AsciiDoc

Add .adoc file extension for AsciiDoc as it's a very popular extension to use and the one recommended by the Asciidoctor project.
Switched line endings to LF for system_hooks.md

It was checked in with Windows style line endings.
Speed up features/notes_on_merge_requests_spec

This spec featured the slowest tests in the entire suite. After some
debugging, the cause was found to be the large commit diff generated by
comparing the stable and master branches.

To fix this, the seed repository was modified to create a simple branch
off of master that consists of three simple commits and minor changes.
The spec was then updated to compare master to this branch instead of
stable. The result is a spec group that runs in under 30 seconds, down
from about 90.
Speed up finders/merge_requests_finder_spec

Uses the :simple merge request factory trait introduced by d166e70; cuts
execution time of this spec in half.
Add public/private/internal traits to :project Factory
Make use of project factory traits
Replace turbolink spinner with nprogress

Signed-off-by: Dmitriy Zaporozhets <dmitriy.zaporozhets@gmail.com>
 Merge branch 'nprogress' into 'master'

Nprogress
Add room placeholder for Slack integration

Signed-off-by: Dmitriy Zaporozhets <dmitriy.zaporozhets@gmail.com>
Merge pull request #6560 from tsigo/visibility-traits

Visibility traits for Project Factory
Merge pull request #6557 from tsigo/faster-merge-request-features

Speed up features/notes_on_merge_requests_spec
Merge pull request #6535 from docwhat/sys-hooks-eols

Switched line endings to LF for system_hooks.md
Merge pull request #6457 from lol768/patch-1

Fix registration error info typo
Merge pull request #6469 from mojavelinux/master

Add .adoc file extension for AsciiDoc
typo fix
Merge pull request #6568 from skv-headless/patch-1

typo fix