Update libraries version and add scala 2.10.4, 2.11.0

Update crossScalaVersions for Scala 2.11.0
and some modifications.

* Add Travis CI settings.  
I have confirmed the build success at my repository.  
[![Build Status](https://travis-ci.org/zaneli/slf4s.png?branch=scala-2.11.0)](https://travis-ci.org/zaneli/slf4s)
* Update dependent libraries version.
* Force a particular sbt version.(latest version, 0.13.2)