add job service to be able to cancel plot requests

pdb-js/src/app/plot.service.ts

@@ -50,6 +50,10 @@ export class PlotService {
     };
     return this.http.get<AutocompleteResult>('//'+window.location.hostname+':'+window.location.port+'/api/autocomplete', options);
   }
+
+  abort(submitterId: string): Observable<void>{
+    return this.http.delete<void>('//'+window.location.hostname+':'+window.location.port+'/api/plots/'+submitterId)
+  }
   
   sendPlotRequest(plotRequest: PlotRequest): Observable<PlotResponse>{
     
@@ -219,6 +223,7 @@ export class PlotRequest {
     public generateThumbnail : boolean,
     public intervalUnit: string,
     public intervalValue: number,
+    public submitterId: string,
     public renderBarChartTickLabels: boolean = false){}
   
   copy(): PlotRequest {