chore(config): use accessors for config properties

Fix #823

Author: mgechev

tools/config/project.config.ts

@@ -3,13 +3,16 @@ import { join } from 'path';
 import { SeedConfig } from './seed.config';
 import { InjectableDependency } from './seed.config.interfaces';
 
+import {Overwrite} from '../utils/seed/overwrite_config';
+
 /**
  * This class extends the basic seed configuration, allowing for project specific overrides. A few examples can be found
  * below.
  */
 export class ProjectConfig extends SeedConfig {
 
   PROJECT_TASKS_DIR = join(process.cwd(), this.TOOLS_DIR, 'tasks', 'project');
+  @Overwrite() NPM_DEPENDENCIES: InjectableDependency[];
 
   constructor() {
     super();