Notify email to mentioned users; show participants ala github on issuables

Database seeding failing

[Doc] Update 5.0 to 5.1: Recompile assets

Fix wrong file versions in update docs (5.2 to 5.3)

add db index for authentication_token column in users table

Conflicts:
	doc/install/installation.md

Recompiling assets on the update is needed or main menu appearance may not load properly. This has been mentioned on issues #3722 and #3978.

The command has been tested several by users on those issues and by myself.

Thanks for your time and attention.

Remove unused but slow code

Fix paths to the Contents Markdown pages

Scrum view style milestone view.

Fix spelling error and make sure you never log in as git user so you never have to logout to run sudo.

Switch form from table to plain form without member list