Log Message:
Update ruby-net-ssh-gateway to 2.0.0.

=== 2.0.0 / 26 Jan 2017

* Update net-ssh dependency to 4.0.0 which requires Ruby version >= 2.0 [delano]

=== 1.3.0 / 26 Jan 2017

* Fix for loop_wait option on initialization [mfazekas, tpitale]
* Use bundler and remove remove jeweler [tpitale]
* Use minitest instead of test/unit [tpitale]
* Added Travis CI config [tpitale]