srm-client: Improve startup time

The patch cleans up the srm script and adds the '-XX:+TieredCompilation
-XX:TieredStopAtLevel=1' java options for improved startup speed. On my laptop
this has reduced the time required to run test --srm against system-test with
approximately 40 seconds.

Target: trunk
Require-notes: yes
Require-book: no
Acked-by: Tigran Mkrtchyan <tigran.mkrtchyan@desy.de>
Patch: http://rb.dcache.org/r/6692/