tests: added option to enable MD cache in tests
tests: added option to enable MD cache in tests


gurkerl83/millipede-xtreemfs,gurkerl83/millipede-xtreemfs,gurkerl83/millipede-xtreemfs,gurkerl83/millipede-xtreemfs,gurkerl83/millipede-xtreemfs,gurkerl83/millipede-xtreemfs,gurkerl83/millipede-xtreemfs