Added changes for eblob which supports trace_id
Moved trace_id into TLS.
Removed debug printfs
Merge branch 'master' of github.com:reverbrain/elliptics into trace

Conflicts:
	bindings/cpp/callback_p.h
	bindings/cpp/log.cpp
	bindings/cpp/session.cpp
	bindings/cpp/session_indexes.hpp
	bindings/python/elliptics_python.cpp
	cache/cache.cpp
	example/common.c
	example/config.c
	example/find.cpp
	example/ioclient.cpp
	include/elliptics/backends.h
	include/elliptics/interface.h
	include/elliptics/session.hpp
	indexes/indexes.cpp
	indexes/local_session.cpp
	library/discovery.c
	library/dnet.c
	library/elliptics.h
	library/node.c
	library/notify.c
	library/pool.c
	library/trans.c
Restored missed dnet_state_clean
Merge pull request #218 from shaitan/trace

TLS based Trace