Update Travis CI config to use Ruby 2.2.2 (#387)
Update Travis CI config to use Ruby 2.2.2 (#387)

* Update Travis CI config to use Ruby 2.2

As per https://travis-ci.org/GoogleChrome/samples/builds/144504931#L193, our Travis CI builds are failing because one of the depedencies expects Ruby 2.2. I don't know of any reason not to upgrade, so this change does that.

* Explicitly use Ruby 2.2.2, not 2.2.0

beaufortfrancois/samples,689/samples,GoogleChrome/samples,689/samples,dmurph/samples,GoogleChrome/samples,rsolomakhin/samples,jeffposnick/samples,rsolomakhin/samples,jeffposnick/samples,rsolomakhin/samples,paullewis/samples,GoogleChrome/samples,GoogleChrome/samples,paullewis/samples,dmurph/samples,jeffposnick/samples,paullewis/samples,jeffposnick/samples,beaufortfrancois/samples,beaufortfrancois/samples,GoogleChrome/samples,dmurph/samples,beaufortfrancois/samples,689/samples