_get_jar() is now _get_streaming_jar()
added jars from JarSteps to the upload manager
added test for uploading the jar from a JarStep. it fails, darn.
test passes!
added test for jars on S3
added file:/// special case for jars inside EMR
patched existing test that uses a fake job
removed now useless constant from mockboto
added a test of whether jar steps work at all on hadoop (they don't)
renamed _streaming_args_for_step to _args_for_streaming_step
hadoop now supports JarSteps

mockhadoop's jar now only simulates streaming steps
added a test for what the hadoop runner does with HDFS uris
added test for file:/// URI special case (currently fails)
hadoop runner now special-cases file:/// URIs for jars
squashed stray logging from hadoop fs' path_exists()
fix bad indent in mockhadoop
_build_jar_step() now only takes one arg, for consistency
Merge pull request #781 from davidmarin/hadoop_jar_steps

Hadoop jar steps. Fixes #770, #772.