[Save] Show blocking dialog

Show a blocking dialog while the save action is being performed.

Prevents users from pressing save a second time or performing
further actions while a save is in progress.

Fixes https://github.jpl.nasa.gov/MissionControl/vista/issues/362

platform/commonUI/edit/test/actions/SaveAsActionSpec.js

@@ -100,7 +100,9 @@ define(
                 mockDialogService = jasmine.createSpyObj(
                     "dialogService",
                     [
-                        "getUserInput"
+                        "getUserInput",
+                        "showBlockingMessage",
+                        "dismiss"
                     ]
                 );
                 mockDialogService.getUserInput.andReturn(mockPromise(undefined));
@@ -169,6 +171,19 @@ define(
                 expect(mockDialogService.getUserInput).toHaveBeenCalled();
             });
 
+            it("shows a blocking dialog while waiting for save", function () {
+                mockEditorCapability.save.andReturn(new Promise(function () {}));
+                action.perform();
+                expect(mockDialogService.showBlockingMessage).toHaveBeenCalled();
+                expect(mockDialogService.dismiss).not.toHaveBeenCalled();
+            });
+
+            it("hides the blocking dialog after saving", function () {
+                action.perform();
+                expect(mockDialogService.showBlockingMessage).toHaveBeenCalled();
+                expect(mockDialogService.dismiss).toHaveBeenCalled();
+            });
+
         });
     }
 );