add oauth:authorized and implement true oauth:login

per https://github.com/andreareginato/oauth-ng/issues/16

sorry this pull is kinda nasty as it includes the code that fixes for https://github.com/andreareginato/oauth-ng/pull/18 as well.  I made a new topic branch, but I don't know how to omit outstanding/not yet merged into upstream/master.

The code is really just the last commit: https://github.com/doapp-ryanp/oauth-ng/commit/13ce5b27d6e758004da5dd5a4989fff55a68cf28

Even nastier is the gh-pages updates for this.  You can't make a topic branch from that branch and there is outstanding pull request on it from the `state` pull request docs.  So you'll see another commit on that pull request shortly, for the docs about oauth:authorized and "new" oauth:login

If you know of a better way to handle this merge, please let me know and I'll be happy to modify