Restore Travis CI configuration file, and add setup script.

Using before_script, setup ZeroMQ and JZMQ.

I have confirmed the almost all case success and one case failure at my repository.
https://travis-ci.org/zaneli/scala-zeromq/builds/23945403
> - should raise error if connect does not succeed *** FAILED ***
>   Expected exception org.zeromq.ZMQException to be thrown, but no exception was thrown. (SocketRefSpec.scala:48)

I'm sorry but I can't understand this cause.
(caused by the difference in version of ZeroMQ or JZMQ?
 my setup script is bad?
 or, test code is wrong?)

I hope the Travis CI environment and test result make you resolve the problem.