fix(error message): improve error on ngModule redefinition

- when a user reuses an angular module, i.e. by specifying the same
module
  name in multiple ngDefine calls, redefinition (i.e. adding more
 `module:some.angular.module` dependencies) is not allowed, as angular
  does not allow to re-define module definitions
- added detailed error message to better reflect that issue

Closes #1