[SPARK-4382] Add locations parameter to Twitter Stream

When we request Tweet stream, geo-location is one of the most important parameters. In addition to the track parameter, the locations parameter is widely used to ask for the Tweets falling within the requested bounding boxes. This PR adds the locations parameter to existing APIs.
There are *12* new overloads of `createStream` on top of the existing 4. This seems like big overkill. There should be one version in Java/Scala that takes all arguments, one each that takes minimal arguments, and any others needed to retain binary compatibility. The rest seem superfluous.