Include google person information in the credsExtra field for GoogleEmail2 auth

I only really am interested in a few fields, but it was easier to just return everything.
Instead of encoding to a ByteString and then decoding to Text, how about encoding to text directly with [encodeToTextBuilder](http://hackage.haskell.org/package/aeson-0.8.0.0/docs/Data-Aeson-Encode.html#v:encodeToTextBuilder)? This would also have the nice effect of avoiding `BL.toStrict`, which presents problems for GHC 7.4.