Log with DEFAULT_INSTANCE_ID in the absence of instance id

This patch adds the DEFAULT_INSTANCE_ID to log messages when no
instance id is specified.

Signed-off-by: Josh Abraham <sinisterpatrician@gmail.com>

CHANGELOG.md

@@ -16,6 +16,7 @@
 - `PUT` operations on `/network-interfaces` API resources no longer accept 
   the previously required `state` parameter.
 - The jailer starts with `--seccomp-level=2` (was previously 0) by default.
+- Log messages use `anonymous-instance` as instance-id if no instance-id is set.
 
 ## [0.11.0]
 

src/main.rs

@@ -34,7 +34,7 @@ const DEFAULT_INSTANCE_ID: &str = "anonymous-instance";
 
 fn main() {
     LOGGER
-        .init(&"", None, None, vec![])
+        .init(DEFAULT_INSTANCE_ID, None, None, vec![])
         .expect("Failed to register logger");
 
     // If the signal handler can't be set, it's OK to panic.