KAZOO-2701 retry fax storage

I've been testing it and never hit the condition you mention (attachment is good with fs error). the storage command uses fs api command and waits for the reply. every single time there was an error in fs api the retry did work, even with 4 retries. i'm not sure if this is a bigcouch/haproxy issue or a fs issue, because it takes sometime to give the error and when retried is automatic (64 page fax). i think this is a good fix for now but we could also explore the bgapi.