Reorder the user, password, host, port and database appearances for uniformity.

[juangpc]

Hi,
Trying to add uniformity to the use of the keys (user, password, host, port and database) in the code and docs.
I see the use of fields scattered in code and in documentation, in many different orders. Figured it could help for clarity to try to have a similar as possible order. Makes it easier to see if you're forgetting one of them, identify changes, etc...

New to pg. Figured could be helpful. Thanks for a great package.

Fun fact (Had to check it out).
When you have 3 terms -> ternary.
when you have 4 terms -> quaternary. (ref.stack exchange discussion)

[brianc]

Hi! Thanks for the house keeping PR! Things like this add up overtime to a generally better code base & I appreciate it! 😄