Merge pull request #539 from agend/master

fixed check for gcc version: support for noexcept on class constructor a...
session: when using send-to-all-backends set backend id via dnet_session_set_direct_backend() call. We can not extend dnet_trans_control because of ABI.
find: set DNET_FLAGS_DIRECT_BACKEND flag which will force client code to set backend ID (session/finer will have direct backend id set to the last backend id from the route table)
backend: moved object size calc (getting into account total size and io->size/io->offset) into common header from eblob. Implemented proper timestamp reading in file backend
state: dnet_state_create() reference counter fix/change

Code comments contain more information about this commit, here is a small note.
dnet_state_create() previously returned state with only one reference being held.
And it could be released by network thread, who actually owns state after it is added into epoll().

But some callers (creating threads) can perform operations on this state, thus it must not be freed
by network thread. dnet_state_create() now returns state with 2 reference being held:
1 for network thread (owner of the state)
2 for caller thread, and caller must release that state after it finished working with it.
Merge branch 'master' of github.com:reverbrain/elliptics
file: do not chroot to root dir, since with multuple backends there are multuple roots in the same process context
run_servers: added 2 seconds sleep to wait for server/app initialization
test: monitor: dump json stat into file if json decoder failed
test: write_cas: do not use lambda, use plain function instead (checking RHEL6 issue)
test: monitor: open json dump file for writing
srw: added log-output: true into application profile to dump crashlog into log
srw: added log-output: true into application's profile top level to dump crashlog into log
rapidjson: correctly handle NaN values, small double values
srw: removed dumping @info result to the log
monitor: using handystats library to gather runtime statistics

 - instrumented process_raw and cache
 - compile time option WITH_STATS allows to enable/disable handystats
   instrumentation at compile time (WITH_STATS is ON by default)
 - integration into monitor service with new category "stats"
   (native, http, python binding)
 - config: "handystats_config" option bears the name of handystats config
   file, could be omitted, handystats will run on defaults then
monitor: complete replacement of react
monitor: added support for formatted metrics names
monitor: update to handystats 1.9.8
monitor: io input/output/commands stats fixed and improved