Previously after a SessionExpired event the context->zookeeper field was
reinitialized with the old expired ZooKeeper instance. This led to inability
to get new paths. Better not cache the ZooKeeper instance and get it at the
start of each request.
* Make separate libs Common/ZooKeeper and Common/ConfigProcessor
renamed: dbms/src/Common/StringUtils.h -> dbms/src/Common/StringUtils/StringUtils.h
* Fix space
* Fix data in system.build_options
* merge
* merge