Make cancel work on connection dialog

jupyter-openbis-extension/static/connectionDialog.js

@@ -226,11 +226,17 @@ define(
                     state.connection.name = state.connection.candidateName
                 }
 
+                function onCancel() {
+                    state.connection.candidateName = state.connection.name
+                }
+
                 dialog.modal({
                     body: uploadDialogBox,
                     title: 'Choose openBIS connection',
                     buttons: {
-                        'Cancel': {},
+                        'Cancel': {
+                            click: onCancel
+                        },
                         'Choose connection': {
                             class: 'btn-primary btn-large',
                             click: onOk