Fix error response html formatting; expose Application start/stop unit methods

src/http/response/ErrorResponseFactory.ts

@@ -76,7 +76,7 @@ Stack trace:
             str += `
                 <pre><code>
 Context:
-${Object.keys(context).map(key => `    - ${key} : ${context[key]}\n`)}
+${Object.keys(context).map(key => `    - ${key} : ${context[key]}`).join('\n')}
                 </code></pre>
                 `
         }

src/lifecycle/Application.ts

@@ -174,7 +174,7 @@ export class Application extends Container {
         }
     }
 
-    protected async startUnit(unit: Unit) {
+    public async startUnit(unit: Unit) {
         const logging: Logging = this.make<Logging>(Logging)
 
         try {
@@ -190,7 +190,7 @@ export class Application extends Container {
         }
     }
 
-    protected async stopUnit(unit: Unit) {
+    public async stopUnit(unit: Unit) {
         const logging: Logging = this.make<Logging>(Logging)
 
         try {