Applies workspace substitution to the restart command. (#219)

Fixes #217 

* Sub in the new restart command.

* Addition of restart workspaces to sub.

* Fix for WORKSPACE substitutions into restart.

* Correction to override restart instead of cmd.

maestrowf/datastructures/core/study.py

@@ -575,8 +575,8 @@ def _stage(self, dag):
                 node = copy.deepcopy(node)
                 node.run["cmd"] = cmd
                 node.run["restart"] = r_cmd
-                LOGGER.debug("New cmd = %s", cmd)
-                LOGGER.debug("New restart = %s", r_cmd)
+                logger.debug("New cmd = %s", cmd)
+                logger.debug("New restart = %s", r_cmd)
 
                 dag.add_step(step, node, workspace, rlimit)