goauth2: add -auth -token -redirect, and -ap flags allowing the example to work with other OAuth2 providers Tested with Microsoft, Google, and Meetup
goauth2: add -auth -token -redirect, and -ap flags
allowing the example to work with other OAuth2 providers
Tested with Microsoft, Google, and Meetup

R=adg
CC=golang-dev
http://codereview.appspot.com/6459103

Committer: Andrew Gerrand <395a7d33bec8475c9b83b7d440f141bcbd994aa5@golang.org>

udhos/goauth2,jeisenberg/goauth2,aquarat/goauth2,djacobow/goauth2,mattga/goauth2,happydpc/goauth2,desireebisco/goauth2,avisri/goauth2,smagic39/goauth2,odeke-em/goauth2,badu/goauth2,treetopllc/goauth2,epelc/goauth2,skyeunknown084/goauth2,combucha/goauth2,imrickrick/goauth2,stanwu/goauth2,pkieltyka/goauth2,lvzhihao/goauth2,MrDangerous/goauth2,hiteshjoshi/goauth2,bhcleek/goauth2