Major improvement in OSM charms

- Adapt all new operator charms to use the same pattern. They are all
using now this library that encapsulates the common logic for all
charms: https://github.com/davigar15/ops-lib-charmed-osm. That will be
eventually moved to gitlab, when it has a PyPI repository available
- Add unit tests to all charms
- Modify installer and bundles to point to the new charms
- Improve the build.sh script for building the charms

Change-Id: I0896ceb082d1b6a76b3560c07482a4135a220a3f
Signed-off-by: David Garcia <david.garcia@canonical.com>
diff --git a/installers/charm/ro/metadata.yaml b/installers/charm/ro/metadata.yaml
index f29f4bc..eea0e9e 100644
--- a/installers/charm/ro/metadata.yaml
+++ b/installers/charm/ro/metadata.yaml
@@ -40,11 +40,14 @@
     upstream-source: "opensourcemano/ro:8"
 provides:
   ro:
-    interface: osm-ro
+    interface: http
 requires:
   kafka:
     interface: kafka
+    limit: 1
   mongodb:
     interface: mongodb
+    limit: 1
   mysql:
     interface: mysql
+    limit: 1