Fix check of an app's presence in INSTALLED_APPS
Fix check of an app's presence in INSTALLED_APPS

In TenantSyncRouter, the logic to check whether an app is a tenant app or shared app was too simplistic. Django 1.7 allows two ways to add an app to INSTALLED_APPS. 1) By specifying the app's name, and 2) By specifying the dotted path to the app's AppConfig's class. This commit ensures that we check for the latter case as well. https://docs.djangoproject.com/en/1.8/ref/applications/#configuring-applications
tomturner/django-tenants,tomturner/django-tenants,sigma-geosistemas/django-tenants,sigma-geosistemas/django-tenants,tomturner/django-tenants