Update git submodules

* Update swift from branch 'master'
  - Client should retry when there's just one 404 and a bunch of errors
    
    During a rebalance, it's expected that we may get a 404 for data that
    does exist elsewhere in the cluster. Normally this isn't a problem; the
    proxy sees the 404, keeps digging, and one of the other primaries will
    serve the response.
    
    Previously, if the other replicas were heavily loaded, the proxy would
    see a bunch of timeouts and the fresh (empty) primary, treat the 404 as
    good, and send that on to the client.
    
    Now, have the proxy throw out that first 404 (provided it doesn't have a
    timestamp); it will then return a 503 to the client, indicating that it
    should try again.
    
    Add a new (per-policy) proxy-server config option,
    rebalance_missing_suppression_count; operators may use this to increase
    the number of 404-no-timestamp responses to discard if their rebalances
    are going faster than replication can keep up, or set it to zero to
    return to the previous behavior.
    
    Change-Id: If4bd39788642c00d66579b26144af8f116735b4d

swift

@@ -1 +1 @@
-Subproject commit 06091172c218929bcee9c66c50e846acd8326a32
+Subproject commit 754defc39c0ffd7d68c9913d4da1e38c503bf914