fix(@angular-devkit/core): allow scoped names for workspace projects

Library projects support scoped package names as project names.

Author: clydin

packages/angular_devkit/core/src/workspace/definitions.ts

@@ -201,8 +201,8 @@ export class ProjectDefinitionCollection extends DefinitionCollection<ProjectDef
   }
 
   private _validateName(name: string): void {
-    if (typeof name !== 'string' || !/^[a-zA-Z][.0-9a-zA-Z]*(-[.0-9a-zA-Z]*)*$/.test(name)) {
-      throw new Error('Project name must be a valid npm package name without a scope.');
+    if (typeof name !== 'string' || !/^(?:@\w[\w\.-]*\/)?\w[\w\.-]*$/.test(name)) {
+      throw new Error('Project name must be a valid npm package name.');
     }
   }