Fix Procfile, update documentation.

[linneakirby]

Fix Procfile:

• Before this change, the Procfile only defines the server
• After this change, the Procfile runs the server.

Update documentation:

• Before this change, OAUTH_CLIENT_{ID,SECRET} are mentioned in the README,
  but the application actually uses GITHUB_APPLICATION_CLIENT_{ID,SECRET}.

[timwis]

So odd, this has stopped working for JKAN installations too, and now I'm wondering how it ever worked, since Procfile only defines the server but doesn't run it.

@linneakirby, I think you may have misread about the GITHUB_APPLICATION_CLIENT_... bits though - if you look through the code, it does use OAUTH_CLIENT_... - the github_ one is only placeholder text. So I think if you remove that change from this PR, perhaps it could be merged.

[bergvall95]

@timwis I had to look at the code to figure this out myself. I think the language explaining it could be a bit more clear that the keys in the environment variables need to be OAUTH_CLIENT_ID and OAUTH_CLIENT_SECRET. Couldn't figure out why it wasn't working when I was using the GITHUB_APPLICATION.. keys.

[timwis]

It's been awhile since I was looking at this, but I vaguely recall the issue may have been which branch gets deployed. Development is the default branch, but the deploy button deploys the master branch, I believe.

[bergvall95]

@timwis I was just talking about the documentation about the names of the environment variables. Pretty long time after to tag you on that, sorry about that!