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/bgpcep/BUILD b/providers/bgpcep/BUILD
index 1ca61bc..9910827 100644
--- a/providers/bgpcep/BUILD
+++ b/providers/bgpcep/BUILD
@@ -20,6 +20,11 @@
     category = "Provider",
     description = "BGPCEP providers.",
     included_bundles = BUNDLES,
+    required_apps = [
+        "org.onosproject.tunnel",
+        "org.onosproject.bgp",
+        "org.onosproject.pcep-api",
+    ],
     title = "BGPCEP Provider",
     url = "http://onosproject.org",
 )