logs: added log that net thread has been finished.
api: added resetting namespace by setting empty namespace.
Python: fixed missing _node at cloned session.
recovery: skipping on iteration key with zero size of data.
recovery: added  output format for statistics.
python: added set_backend_ids method to elliptics.Session.
dnet_balancer: added option '-u/--update' that turns no remote update ids on backends after balancing.
dnet_balancer: added outputing final dht spread between nodes/backends.
backends: do not process commands aimed to uninitialized backend.
backend: eblob_init sets errno on fail - use it for returning correct error code.
python: removed duplicated calls - use bp::bases for inheritance between different result_entry and base callback_result_entry.
python: added 'backend_id', 'trace_id' and 'trans' to callback_result_entry.
recovery: fixed warnings.
recover: fixed  and  recovery from dump. Added test case for recovering keys from dump.
python: use dict if OrderedDict is not available.
recover: skips keys that are missed on all nodes.
recover: do not print error on lookup fail while recovering keys from dump - fail is an ok situation. Count lookups before run async lookup - to determine correctly that all async lookups are completed.
route: do not request route list if node flags includes DNET_CFG_NO_ROUTE_LIST
Merge pull request #549 from shaitan/master

Updates and fixes