Merge pull request #4 from hardyoyo/update-for-janeway-1.5.0

Add required on_delete to models.py so this plugin is compatible with Janeway 1.5.0

models.py

@@ -3,7 +3,7 @@
 from repository.models import Repository
 
 class RepoEZIDSettings(models.Model):
-    repo = models.OneToOneField(Repository)
+    repo = models.OneToOneField(Repository, on_delete=models.CASCADE)
     ezid_shoulder = models.CharField(max_length=50)
     ezid_owner = models.CharField(max_length=50)
     ezid_username = models.CharField(max_length=200)