Recommend synchronous DELETE requests return 204

[keithamus]

I feel like we've reached enough of a consensus in #15 to attempt to PR a change, so this fixes #15.

Wording has been changed to suggest all responses should provide the latest copy of the data, further suggesting that (synchronous) DELETEs should return a 204 No Content.

[rikvanmechelen]

I was the original creator of #15
So i am totally for the change. I followed the discussion in #15 and agree with it as well.
However, since this is a guide, it should leave both possibilities open, and include the reasoning of why one might want to chose a 204 above a 200 for a delete.

[keithamus]

I think by virtue of it being a guide, it has a huge caveat emptor label over everything anyway. My personal feeling about this is that it should be prescriptive (and it all pretty much is so far), because leaving stuff open to interpretation means varying qualities of implementation.

[geemus]

I would also prefer a single prescriptive option, wherever possible. I think the exceptional case would be synchronous vs asynchronous. That said, one of my colleagues is pulling on a few extra threads in #15 that I'd like to continue discussing a bit more before we decide which possibility we think is best.