DP-178 Updated perf so that it can launch and terminate a cluster

It works in two modes: It can take an emr-launch-config with no steps and just launch cluster from there and then run a benchmark. Alternatively, it can take an emr-launch-config to launch emr, run a job, and terminate emr

Squashed commit of the following:

commit 7b5f739ceebb40e2f7a322fa07375e78a0b4696e
Author: Abin Shahab <ashahab@altiscale.com>
Date:   Wed Nov 13 10:49:07 2013 -0800

    DP-178 Updated Rakefile so that it can locally install

commit b640bf784e0908da38ccf58ce079291d0a098cae
Author: Abin Shahab <ashahab@altiscale.com>
Date:   Tue Nov 12 16:31:31 2013 -0800

    DP-178 perf works for launching a job

commit 044d74e097c38161d8bb340fff02b809bcc7a0ac
Author: Abin Shahab <ashahab@altiscale.com>
Date:   Tue Nov 12 09:59:17 2013 -0800

    Fixed tags

commit f45c3d3c3b82c8a9ecb41a2293ec945eae45b423
Author: Abin Shahab <ashahab@altiscale.com>
Date:   Tue Nov 12 09:50:22 2013 -0800

    DP-178 Initial emr launch with tagging