Dockerfiles to run the XtreemFS services in containers.

Service configuration files are expected to be mapped into /xtreemfs_data. The
config files have to be named dirconfig.properties, mrcconfig.properties,
osdconfig.properties, and schedulerconfig.properties. A new service can be
startet for instance by running

docker run -v /ssd:/xtreemfs_data -p 32640:32640 -t -d xtreemfs/xtreemfs-harness-osd:latest
docker run -v /ssd:/xtreemfs_data -p 32636:32636 -p 32638:32638 -p 32642:32642 -p 30080:30080 -t -d xtreemfs/xtreemfs-harness-manager

to run an XtreemFS OSD while the config is stored in /ssd/osdconfig.properties
on the host. Network ports have to be mapped adequately while executing "docker
run". Required ports are 32636 for the MRC, 32638 for the DIR, 32640 for the
OSD, 32642 for the reservation scheduler, and 8080 for the IRM-XtreemFS.