Expose more homeserver.yaml options as values

[typokign]

The most useful settings in homeserver.yaml are already mapped to values, mostly under the matrix: object, but there is a ton of additional configuration possible.

Organize, implement, and document as many homeserver.yaml settings as possible, with sane and secure defaults.

[Arkaniad]

This is just a tiny part of this, but I added an option to set the PostgreSQL port to support non-standard deployments. Created PR #19

[Routhinator]

Missed this issue, #22 adds some security related items.