Monitor: Added extra check that monitor is still alive after acquiring rwlock.
Merge pull request #363 from shaitan/master

Monitor: Added extra check that monitor is still alive after acquiring rowlock. (master)
cache: Stop lifecheck thread at node->need_exit

So lifecheck thread will stop at the same time as io/net/check
threads, so server stop will be speeded up for a bit.
Merge pull request #364 from IIoTeP9HuY/io_stats

Cache: Compilation on gcc4.4 fixed
Merge pull request #365 from euroelessar/cache_stop

cache: Stop lifecheck thread at node->need_exit
Core: Missed error notification added
Merge branch 'master' of https://github.com/IIoTeP9HuY/elliptics into io_stats
Cache: Time stats usage example updated
Cache: time_stats are now header only
React added as submodule