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/pcep/BUILD b/providers/pcep/BUILD
index a0e6254..fa0a676 100644
--- a/providers/pcep/BUILD
+++ b/providers/pcep/BUILD
@@ -16,6 +16,8 @@
     required_apps = [
         "org.onosproject.pcep-api",
         "org.onosproject.optical-model",
+        "org.onosproject.tunnel",
+        "org.onosproject.bgp",
     ],
     title = "PCEP Provider",
     url = "http://onosproject.org",