JCLOUDS-342: Retry on HTTP 408 for swift

To repro issue 342, the following steps were taken:
 - Spawn 500 parallel / 2000 total putBlobs to cloudfiles-uk
 - issue a SIGSTOP
 - wait 60 seconds
 - issue a SIGCONT

Without this patch, there are several hundred 408s.
With this patch, these are retried and complete successfully.