Add tests for image location manipulation

This adds tests for the currently untested locations support in
images. A feature must be enabled for this to work, so a feature
flag is added to control it.

Change-Id: I779c959096b3aa9cc3d0fbf1e3c506a22d0a49fb
diff --git a/releasenotes/notes/image_multiple_locations-cda4453567953c1d.yaml b/releasenotes/notes/image_multiple_locations-cda4453567953c1d.yaml
new file mode 100644
index 0000000..c8a026e
--- /dev/null
+++ b/releasenotes/notes/image_multiple_locations-cda4453567953c1d.yaml
@@ -0,0 +1,8 @@
+---
+features:
+  - |
+    Add a new config option
+    `[image_feature_enabled]/manage_locations` which enables
+    tests for the `show_multiple_locations=True` functionality in
+    glance. In order for this to work you must also have a store
+    capable of hosting images with an HTTP URI.