[RFC] Simplified Homebrew formula

Removed unnecessary cmake modifications, and manual building of
dependencies. Updates to Makefile remove the need.
> Very true. I'm fine with whatever, just keep in mind the "Install" page is directed towards "end users".

Took a shot at it, hope it's an improvement. I also moved the section about required build tools to the building page; I think this belongs on a "dev" page rather than on a "user" page.