1. Implemented drill connection management.  A connection pool is created so that for each suite that uses a unique schema (corresponding to an entry in the workspaces list in the storage plugins), there is a connection established for it.  Connections are closed (along with its Statements) properly when tests are completed.
2. As a result of the fix above, the -u option (connection URL) is no longer required in the test execution command line.  All information is programmatically obtained via the test properties file (e.g., zookeeper) and the test definition files (e.g., schema strings).  Updated README.md and run tests script.
3. Fixed an issue with drillbit connection problems (Drillbit endpoint not found).