Use quotes everywhere where passwords are used/generated

[LindsayHill]

Documentation should make it clear that passwords, etc should be quoted when used/generated via CLI.

This is to avoid issues like this StackStorm/st2#3216 where the intention is to have a password like pas$word.

If a user enters st2 auth user -p pas$word, the shell will expand $word, usually to a blank string. It should be entered as st2 auth user -p 'pas$word'. Similarly when htpasswd is used to generate a password hash.

Locations such as this should include a note on escaping passwords https://docs.stackstorm.com/authentication.html?highlight=st2%20auth#usage, and we should always use single quotes around passwords where we use st2 auth in the docs.