Decouple Scope lifecycle from Weave lifecycle

- Run the Weave integrations regardless of if weave is detected.
- Make everything backoff and not spam the logs.
- Add miekg dns to vendor.
- Have the app periodically register with weaveDNS, and the probe do lookups there.
- Decide what the local networks are at runtime, not once at startup.
- Correctly resolve app ids, fixes #825

test/exec/exec.go

@@ -60,6 +60,14 @@ func (c *mockCmd) Kill() error {
 	return nil
 }
 
+func (c *mockCmd) Output() ([]byte, error) {
+	return ioutil.ReadAll(c.ReadCloser)
+}
+
+func (c *mockCmd) Run() error {
+	return nil
+}
+
 func (b *blockingReader) Read(p []byte) (n int, err error) {
 	<-b.quit
 	return 0, nil