Resolve "Root issues and stage-out with SPANK"

At the end, stage-out in root installation was never implemented, so this merge request does it:

1. Stage-in (and waiting until copy happens, bool in trasfer_datasets)
2. Stage-out (and waiting until copy happens)
3. terminates adhoc fs
4. removes adhoc fs directory.

Some issues with needed environment variables solved, however LIBGKFS_HOSTS_FILE and GKFS_DAEMON and GKFS_CLIENT should be defined in the environment as they are installation dependant.

plugins/slurm/slurmadmcli.c

@@ -740,7 +740,7 @@ slurm_spank_user_init(spank_t sp, int ac, char** av) {
     slurm_debug("%s: %s: job id: %d", plugin_name, __func__, jobid);
 
     /* list of job nodes */
-    hostlist_t hostlist = get_slurm_hostlist(sp);
+    hostlist_t*hostlist = get_slurm_hostlist(sp);
     if(!hostlist) {
         slurm_error("%s: failed to retrieve hostlist", plugin_name);
         return -1;