Raise 401 in API views

[danielpatrickdotdev]

Would it be more appropriate (and specific, so more helpful to the client) to use 401 status when we're unable to validate the API token?

[danielpatrickdotdev]

If you did want to change this, I'm ready to submit a PR (see d2e4cf6). Some of it depends on #47 though, so might be easier to wait until that's resolved.

[inglesp]

Good idea!