Enable simple zoom/drag functionality

Author: Mark Robinson

src/main/resources/static/css/main.css

@@ -44,7 +44,7 @@ body {
 
 #visualisation {
     overflow: auto;
-    padding: 10px;
+    padding: 0;
 }
 
 #graph svg {

src/main/resources/static/js/workflow.js

@@ -48,7 +48,10 @@ require(['jquery', 'bootstrap.modal', 'renderer'],
         var dotGraph = $("#dot").val();
 
         // Initialise graph
-        renderer.init("#graph");
+        renderer.init({
+            element: "#graph",
+            zoom: true
+        });
 
         // Update stage with new dot source
         renderer.render(dotGraph);