use a longer y-axis interval by default

this helps to not miss interesting events

pdb-js/src/app/y-axis-definition/y-axis-definition.component.ts

@@ -9,7 +9,7 @@ import { YAxisDefinition  } from '../plot.service';
 export class YAxisDefinitionComponent {
 
   yAxisScale: string = "LOG10";
-  yAxisUnit: string = "SECONDS";
+  yAxisUnit: string = "MINUTES";
   minYValue: number = 0;
   maxYValue: number = 300;