freemount:  Support non-empty fragment payloads
freemount:  Pad fragments to a multiple of 4 bytes
freemount:  Add send_u32_fragment()
freemount:  Add send_u64_fragment()
freemount:  Add send_string_fragment()
Merge branch 'payloads'
freemountd:  Track the pending request type
freemountd:  Factor out send_response()
freemountd:  Send errors
freemountd:  Implement stat()