At write time:
  - Add the whole sa to the new cdb field named sa instead of storing the key one by one.
  - Store uniquely the uint of the key instead of appending a string.

At read time:
  - Do not build again the sa looking for the cdb value but read the whole sa instead.
  - Do not use extra HEAP memory allocation.
At modification time:
  - Sanitize the resolve by writting the sa from scratch.
  - Use /tmp directory as temporary cdb file.
Replace resolve_find_cdb by the resolve_get_key and resolve_get_sa function.
Replace service_resolve_copy by service_resolve_sanitize.

This reverts commit 87bd69c6.

Thanks for your service! This resolve file was used with s6-rc. The things now are simplier
and flexible.

service Master resolve file is no longer a service incorporate to the DB. It was reorganize to provide mandatory field to be a real Master. This file will now be used to known the global state of the services.

use new name of tree_read_cdb(), tree_resolve_read_master_cdb(), tree_resolve_write_cdb() and tree_resolve_write_master_cdb() function