TonyClient and startTHS.sh should read tony-site.xml config file from TONY_CONF_DIR

[erwa]

TonY clients and the TonY History Server need to use the same value for the location of the history files. The client needs to tell the TonY AM to write to that location and the history server needs to read from that location.

We should define this location in a tony-site.xml file and expect it to be in the directory pointed to by the environment variable TONY_CONF_DIR, which can be set before running TonY clients or the history server.

See #81 (comment) for more context.

[pdtran3k6]

With that being said, my assumption would be that on both client host and history server host, there would be an environment variable TONY_CONF_DIR that points to a tony-site.xml with respect to that host. (The client host doesn't need other history config like keytab, principal, etc., but if that increases the maintenance overhead of tony-site.xml, then we could make them the same for now).