Removed 0.6 from travis, added 0.10

Also stringified the versions as they should be, as it is a yaml file so `0.10` becomes `0.1`, so for versions we should use strings - `"0.10"` stays `0.10`
Merge pull request #1220 from balupton/patch-1

Removed 0.6 from travis (no longer supported by socket.io deps), added 0.10