Updates to the verify student Django admin.

* Ensure that VerificationStatus is append-only and immutable.
* Allow searching by student for verification status.
* Properly pluralize verification status.
* Use ConfigModelAdmin for ICRV config model admin.

lms/djangoapps/verify_student/admin.py

 from ratelimitbackend import admin
+from config_models.admin import ConfigurationModelAdmin
 from verify_student.models import (
     SoftwareSecurePhotoVerification,
     InCourseReverificationConfiguration,
-    VerificationStatus
+    VerificationStatus,
+    SkippedReverification,
 )
 
 
@@ -20,12 +22,39 @@ class VerificationStatusAdmin(admin.ModelAdmin):
     """
     Admin for the VerificationStatus table.
     """
-    list_display = ('id', 'user', 'status', 'checkpoint', 'location_id')
-    search_fields = (
-        'checkpoint',
-    )
+    list_display = ('timestamp', 'user', 'status', 'checkpoint', 'location_id')
+    readonly_fields = ()
+    search_fields = ('checkpoint', 'user')
+
+    def get_readonly_fields(self, request, obj=None):
+        """When editing an existing record, all fields should be read-only.
+
+        VerificationStatus records should be immutable; to change the user's
+        status, create a new record with the updated status and a more
+        recent timestamp.
+
+        """
+        if obj:
+            return self.readonly_fields + ('status', 'checkpoint', 'user', 'location_id', 'response', 'error')
+        return self.readonly_fields
+
+    def has_delete_permission(self, request, obj=None):
+        """The verification status table is append-only. """
+        return False
+
+
+class SkippedReverificationAdmin(admin.ModelAdmin):
+    """Admin for the SkippedReverification table. """
+    list_display = ('created_at', 'user', 'course_id', 'checkpoint')
+    readonly_fields = ('user', 'course_id')
+    search_fields = ('user', 'course_id', 'checkpoint')
+
+    def has_add_permission(self, request):
+        """Skipped verifications can't be created in Django admin. """
+        return False
 
 
 admin.site.register(SoftwareSecurePhotoVerification, SoftwareSecurePhotoVerificationAdmin)
-admin.site.register(InCourseReverificationConfiguration)
+admin.site.register(InCourseReverificationConfiguration, ConfigurationModelAdmin)
+admin.site.register(SkippedReverification, SkippedReverificationAdmin)
 admin.site.register(VerificationStatus, VerificationStatusAdmin)

lms/djangoapps/verify_student/models.py

@@ -974,6 +974,13 @@ class VerificationCheckpoint(models.Model):
     class Meta:  # pylint: disable=missing-docstring, old-style-class
         unique_together = (('course_id', 'checkpoint_name'),)
 
+    def __unicode__(self):
+        """Unicode representation of the checkpoint. """
+        return u"{checkpoint} in {course}".format(
+            checkpoint=self.checkpoint_name,
+            course=self.course_id
+        )
+
     def add_verification_attempt(self, verification_attempt):
         """ Add the verification attempt in M2M relation of photo_verification
 
@@ -1047,6 +1054,8 @@ class VerificationStatus(models.Model):
 
     class Meta(object):  # pylint: disable=missing-docstring
         get_latest_by = "timestamp"
+        verbose_name = "Verification Status"
+        verbose_name_plural = "Verification Statuses"
 
     @classmethod
     def add_verification_status(cls, checkpoint, user, status, location_id=None):