Allow use of basic auth for security scan endpoints

This will allow the security labeler to send a pull secret to retrieve security information for a manifest

Fixes https://jira.coreos.com/browse/QUAY-1087

endpoints/api/test/test_secscan.py

@@ -0,0 +1,30 @@
+import base64
+
+import pytest
+
+from data.registry_model import registry_model
+from endpoints.api.test.shared import conduct_api_call
+from endpoints.api.secscan import RepositoryImageSecurity, RepositoryManifestSecurity
+
+from test.fixtures import *
+
+@pytest.mark.parametrize('endpoint', [
+  RepositoryImageSecurity,
+  RepositoryManifestSecurity,
+])
+def test_get_security_info_with_pull_secret(endpoint, client):
+  repository_ref = registry_model.lookup_repository('devtable', 'simple')
+  tag = registry_model.get_repo_tag(repository_ref, 'latest', include_legacy_image=True)
+  manifest = registry_model.get_manifest_for_tag(tag, backfill_if_necessary=True)
+
+  params = {
+    'repository': 'devtable/simple',
+    'imageid': tag.legacy_image.docker_image_id,
+    'manifestref': manifest.digest,
+  }
+
+  headers = {
+    'Authorization': 'Basic %s' % base64.b64encode('devtable:password'),
+  }
+
+  conduct_api_call(client, endpoint, 'GET', params, None, headers=headers, expected_code=200)