Fixes for problems with starting and stopping apps in a minimal system

- Missing app dependencies
- Incorrect provider registrations
- Fatal execeptions thrown when external resources are not present

Change-Id: I3fdcf0666c88a47f399a722a9ab549d1104ff40e
diff --git a/providers/ovsdb/host/BUILD b/providers/ovsdb/host/BUILD
index 63e86f7..b59626e 100644
--- a/providers/ovsdb/host/BUILD
+++ b/providers/ovsdb/host/BUILD
@@ -11,6 +11,7 @@
     app_name = "org.onosproject.ovsdbhostprovider",
     category = "Provider",
     description = "OVSDB Host provider.",
+    required_apps = ["org.onosproject.ovsdb-base"],
     title = "OVSDB host Provider",
     url = "http://onosproject.org",
 )