margo context id is not the id of the host that send the request. Is the
internal context id of local margo instance.

 - Use regular expression to parse lines
 - More consistent error handling
 - More comprehensive error messages

Implement proper error propagation and handling on get_dirents RPC.
Error happening on the deamon are now embedded on the returned response
and the client throws an exception once he receives the response.

CCI plugin have been tagged as deprecated in the Mercury library. We
where using it just for verbs, OFI+verbs can be used now as replecement.

Shared-memory communication can be disabled through cmake
compile time option `-DUSE_SHM:BOOL=OFF`

Refactored initialization code.

 - More detailed logging
 - Use exceptions to better propagate errors
 - Log signal type before shutdown