Update help string for --restart to make clear it applies to assessor…

…s of a given type. (#393)

* Removed logic that always sets former status to None if --restart is present.

* Updated help string for --restart to match behavior.

old: Restart the assessors by switching the status for all assessors found to NEED_TO_RUN and delete previous resources.

new: Restart the assessors by switching the status for all assessors \
found to NEED_TO_RUN and delete previous resources.

bin/Xnat_tools/XnatSwitchProcessStatus

@@ -674,8 +674,8 @@ the assessors from -t you changed are inputs to those assessors."
                         action="store_true", help=_h)
     parser.add_argument("--fullRegex", dest="full_regex", action='store_true',
                         help="Use full regex for filtering data.")
-    _h = "Restart the assessors by switching the status for all assessors \
-found to NEED_TO_RUN and delete previous resources."
+    _h = "Restart all assessors of a given process type by switching the \
+git status to NEED_TO_RUN and delete previous resources."
     parser.add_argument("--restart", dest="restart", action='store_true',
                         help=_h)
     _h = "Rerun the assessors by switching status to NEED_TO_RUN for \