Move titan-dist test resources to test-classes

The titan-dist pom prior to this commit copied test resources to the
target/classes directory.  This doesn't get included in any of Titan's
release assemblies right now, but it's fragile.  Moved these resources
-- none of which should ever be included in a release archive -- to
target/test-classes to better reflect their function and reduce the
risk of accidental inclusion in future releases.
Add test of gremlin.sh gremlin-script.groovy

This test checks that gremlin.sh interprets a single command-line
argument, when present, as the path to a script file to be evaluated
and whose additions to the scriptengine variable binding will be
available at the prompt eventually presented to the user.

The sample script used in the test sets and checks these four
variables:

test_i = 2 + 2
test_g = new TinkerGraph()
test_hadoop_class = HadoopFactory.class
test_titan_class = TitanFactory.class

This is for #824
Make gremlin.sh process an arg as a gremlin script

Fixes #824