Fixed imports for appengine/cloudsql (#700)

* Fixed broken import for appengine/cloudsql

appengine.go
import path of appengine/cloudsql has changed to google.golang.org/appengine/cloudsql - Fixed.

* Added my name to the AUTHORS

AUTHORS

@@ -60,6 +60,7 @@ Paul Bonser <misterpib at gmail.com>
 Peter Schultz <peter.schultz at classmarkets.com>
 Rebecca Chin <rchin at pivotal.io>
 Runrioter Wung <runrioter at gmail.com>
+Robert Russell <robert at rrbrussell.com>
 Shuode Li <elemount at qq.com>
 Soroush Pour <me at soroushjp.com>
 Stan Putrya <root.vagner at gmail.com>

appengine.go

@@ -11,7 +11,7 @@
 package mysql
 
 import (
-	"appengine/cloudsql"
+	"google.golang.org/appengine/cloudsql"
 )
 
 func init() {