fix(app): simplify app quit process

Remove redundant code relating to the app close/quit process.

app/lib/zap/controller.js

@@ -199,9 +199,6 @@ class ZapController {
     if (this.neutrino) {
       this.neutrino.stop()
     }
-
-    // Give the grpc connections a chance to be properly closed out.
-    return new Promise(resolve => setTimeout(resolve, 200))
   }
 
   onTerminate() {

app/main.dev.js

@@ -99,18 +99,6 @@ app.on('ready', () => {
     }
   })
 
-  /**
-   * Add application event listener:
-   *  - quit app when window is closed
-   */
-  app.on('window-all-closed', () => {
-    mainLog.debug('app.window-all-closed')
-    // Respect the OSX convention of having the application in memory even after all windows have been closed
-    if (process.platform !== 'darwin') {
-      app.quit()
-    }
-  })
-
   /**
    * Add application event listener:
    *  - Stop gRPC and kill lnd process before the app windows are closed and the app quits.