https://www.ruby-lang.org/en/news/2013/11/22/heap-overflow-in-floating-point-parsing-cve-2013-4164/

SSH is pronounced as /es es aged/, so we need "an" instead of "a".

Isn't 5.4 current stable?

This reverts commit 670e1be7.

This reverts commit b5cd66d4.

Additional unicorn -> puma reference update

Updated incorrect/outdated references to unicorn.rb; changed to puma.rb

I've moved the instruction in question to the the 
'Configure GitLab DB settings'. Can't change permission to a file that doesn't already exist 

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

addresses gitlabhq/gitlabhq#3809