Resolve read/write can be faster.

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.