This defers the creation of request paths until a
client is actually instantiated. Previously this initialization
happened when REFITConfig loaded the client class, which
slows down the configuration check.

When passing '--check' as first argument, then an experiment
will run a basic configuration check.

Previously only variant options were checked to actually override an
entry from refit-defaults. This now applies to all override options.

The implementation has moved to benchmark.py as JavaTestRun.
Wrapping the command with ssh is now a separate function and
gen_remote_java_cmd now also accepts an optional command prefix.