Add benchmarking scripts for Geode-Redis module

Add the following scripts to the Geode-Redis module, in the "performanceTest" directory:

• aggregator.sh runs the actual tests
• benchmark.sh handles validating the redis server (e.g. starting and stopping Geode Redis if needed), then runs aggregator.sh
• shacompare.sh takes two git SHAs as arguments and runs benchmark.sh on each of them, generating separate output files for each.