Move from using redirect() to raw Location: header.
This allows custom URL schemes if required.
OAuth allow - explicitly set URL to return to.
This solves the IE issue whereby IE doesn't always send the referrer header.
Merge remote-tracking branch 'richsage/oauth-redirection-change'
Merge remote-tracking branch 'richsage/oauth-ie-fix'
Merge branch 'master' of git://github.com/joindin/joind.in