Proposal for sbt-based project

[jcjimenez]

Hi All, this is my proposal for migrating to sbt (#58). You may notice there are some minor differences between the dependencies in the original pom.xml which were done to address problems in Scala version conflicts or eviction warnings like the following:

[warn] There may be incompatibilities among your library dependencies.
[warn] Here are some of the libraries that were evicted:
[warn] 	* com.fasterxml.jackson.module:jackson-module-scala_2.11:2.6.5 -> 2.9.0
[warn] 	* com.twitter:chill_2.11:0.8.0 -> 0.9.2
[warn] 	* org.json4s:json4s-jackson_2.11:3.2.11 -> 3.5.3
[warn] Run 'evicted' to see detailed eviction warnings

Lastly, I had to remove these two calls from one of the tests because those #close() methods aren't present in the 3.2.5 version of hadoop-gremlin (it looks like they are in the current SNAPSHOT, so not sure how those methods were available via the pom.xml project):

        HadoopPools.close();
        KryoShimServiceLoader.close();

Lastly, not sure how to run the test in Travis, so I removed the test task from the .travis.yml =(

[khdang]

This is awesome. Thanks, @jcjimenez! Let us look into the dependency changes that you mentioned.