feat(gen): add functions for adding TS public/private keywords

Author: Andrew Koroluk

Diff for: src/generators/generator-base.js

@@ -49,12 +49,19 @@ export class Base extends YoBase {
   to() {
     return this.filters.expect ? ').to' : '.should';
   }
+
+  public() {
+    return this.filters.ts ? 'public ' : '';
+  }
+  private() {
+    return this.filters.ts ? 'private ' : '';
+  }
 }
 
 export class NamedBase extends Base {
   constructor(...args) {
     super(...args);
-    
+
     this.argument('name', { type: String, required: true });
 
     var name = this.name.replace(/\//g, '-');