feat: add the ability to run with '--json' and output the result (#78)

* addition-of-json-flag

* Set output of npn audit

src/audit.ts

@@ -7,7 +7,7 @@ export class Audit {
   stdout = ''
   private status: number | null = null
 
-  public run(auditLevel: string, productionFlag: string): void {
+  public run(auditLevel: string, productionFlag: string, jsonFlag: string): void {
     try {
       const auditOptions: Array<string> = ['audit', '--audit-level', auditLevel]
 
@@ -15,6 +15,10 @@ export class Audit {
         auditOptions.push('--production')
       }
 
+      if (jsonFlag === 'true') {
+        auditOptions.push('--json')
+      }
+
       const result: SpawnSyncReturns<string> = spawnSync('npm', auditOptions, {
         encoding: 'utf-8',
         maxBuffer: SPAWN_PROCESS_BUFFER_SIZE