[ADF-2035] Drag and drop is not working on Processes - attachment List (#2736)

* fix upload for process attachment list
export ActivitiContentService
ProcessService.createOrUpdateProcessInstanceVariables has incorrect method signature

* fix signature methods

* fix test parameters

lib/process-services/task-list/services/task-upload.service.ts

@@ -0,0 +1,49 @@
+/*!
+ * @license
+ * Copyright 2016 Alfresco Software, Ltd.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+import { AlfrescoApiService, AppConfigService, UploadService } from '@alfresco/adf-core';
+import { Injectable } from '@angular/core';
+import { Observable } from 'rxjs/Observable';
+import 'rxjs/add/observable/throw';
+
+@Injectable()
+export class TaskUploadService extends UploadService {
+
+    instanceApi: AlfrescoApiService;
+
+    constructor(apiService: AlfrescoApiService, appConfigService: AppConfigService) {
+        super(apiService, appConfigService);
+        this.instanceApi = apiService;
+    }
+
+    getUploadPromise(file: any): any {
+        let opts = {
+            isRelatedContent: true
+        };
+        let taskId = file.options.parentId;
+        let promise = this.instanceApi.getInstance().activiti.contentApi.createRelatedContentOnTask(taskId, file.file, opts);
+
+        promise.catch(err => this.handleError(err));
+
+        return promise;
+    }
+
+    private handleError(error: any) {
+        return Observable.throw(error || 'Server error');
+    }
+
+}