Adapting passport-google-oauth for mediawiki

Card: analytics 1356
Worked on the readme and strategy so far
TODO before review:
* examples
* tests
* make sure it works :)

Change-Id: I20f49058014269be10684b38d7f74a5b9dabb436
Merge branch 'master' of ssh://gerrit.wikimedia.org:29418/passport-mediawiki

Conflicts:
	examples/oauth/app.js
	lib/passport-mediawiki-oauth/oauth.js
	package.json

Change-Id: I1e15ef855af707bd4db9abbeaeb37ef03abe5e22