Added Travis CI configuration file, setup script, and build status icon.

Using before_script, setup SSH and test user.

I have confirmed the almost all case success and two case failure at my repository.
https://travis-ci.org/zaneli/jassh/builds/24024449 [![Build Status](https://travis-ci.org/zaneli/jassh.png?branch=travis-ci)](https://travis-ci.org/zaneli/jassh)

* https://travis-ci.org/zaneli/jassh/jobs/24024450#L239
I have confirmed `sh.test("1 == 1")` throw Exception, but `sh.test("1 = 1")` don't throw on Travis CI(Ubuntu).
But on my local environment(CentOS) both `==` and `=` don't throw.
I guess caused by the difference in installed ssh or OS distribution.

* https://travis-ci.org/zaneli/jassh/jobs/24024450#L188
I'm sorry but I have no idea.
(caused by the difference in version of openssh?
Is my setup script bad?
Or, is test code wrong?)

I hope the Travis CI environment and the test result make you resolve the problem.