Rethink routing of projects/organizations

[joshsmith]

Problem

Per @begedin in a PR:

The current layout of /:slug/projects is strange and seems to be lacking. On the other hand /organizations/:slug seems the way to go.

The thing is, having both seems a bit redundant. Is there any specific reasoning to have two, or did it just somehow happen along the way.

Merging the "good" behavior from both places into a single namespace under /:organization_slug seems like the way to go.

It also looks like we started off with /:slugged_route_slug with the impression of users being able to have projects at some point to. Is that still a goal? If not, I think we could rewrite our router and organize our files in a clearer, more understandable way, but it would involve a lot of changed files to do so.

This needs some discussion.