Refactor rhizome_write_file() to use fd not FILE*
rhizome_manifest_set_name_from_path()

Refactor rhizome_fill_manifest() to use it
Refactor rhizome_crypt_xor_block() and add debug
Improve Rhizome manifest setter functions

Remove interactions between rhizome_manifest_set_filesize()
and rhizome_manifest_set_filehash(), since any inconsistency
is caught by rhizome_manifest_validate() in any case
UNFINISHED Implement HTTP POST /restful/rhizome/insert