text: Title: Special key to ignore all migrations inside an app.
  Body: It would be useful to have special key for ignoring all migrations inside an app.
  
  Consider case when we have some third party apps and want to ignore all migrations or for all third party apps at all.
  
  Right now we should do something like this:
  
  ```python
  DTM_IGNORED_MIGRATIONS = [
      ('taggit', '0002_auto_20150616_2121'),
      ('two_factor', '0002_auto_20150110_0810'),
      ('two_factor', '0003_auto_20150817_1733'),
      ('two_factor', '0004_auto_20160205_1827'),
      ('two_factor', '0005_auto_20160224_0450'),
      ('waffle', '0002_auto_20161201_0958'),
  ]
  ```
  
  With the special key, for example, it'll get much better:
  
  ```python
  THIRD_PARTY_APPS = (
      'taggit',
      'two_factor',
      'waffle',
  )
  
  # Apps specific for this project go here.
  LOCAL_APPS = (
      'app_1',
      'app_2',
  )
  
  INSTALLED_APPS = THIRD_PARTY_APPS + LOCAL_APPS
  
  DTM_IGNORED_MIGRATIONS = [
      (app, '*') for app in THIRD_PARTY_APPS
  ]
  ```
  