added an update checker button for library (#172)

* added an update checker button for library

* fixed import path

* fixed progress props to not be inline

* added error handling

* fixed linting issue

src/typings.d.ts

@@ -187,6 +187,15 @@ interface IQueue {
     queue: IDownloadChapter[]
 }
 
+interface IUpdateStatus {
+    running: boolean
+    statusMap: {
+        COMPLETE: number,
+        RUNNING: number,
+        PENDING: number
+    }
+}
+
 interface PreferenceProps {
     key: string
     title: string