Adding Gson to Android JSON parser comparison

[update2] Tests have been improved with warmup and multiple iterations

In the comment to my post from yesterday where I compared performance of three JSON parsers on Android, Carlos suggested to try also Gson. And that was a good idea. Its streaming API seems to be the fastest one to parse Twitter public timeline. Again, test sources are in GitHub and feel free to suggest any enhancements.

[update] It seems that Gson and Jackson compete pretty well. In fact I have a feeling that Jackson is faster more often then Gson, so I'll try to come up with more tests, with multiple passes or something like that. Any advice on how to measure this correctly is appreciated.