Introduce replication_sync_timeout configuration option

[locker]

box.cfg{replication = ...} doesn't return until it synchronizes with a quorum, i.e. until the replication lag is less than box.cfg.replication_sync_lag for at least box.cfg.replication_connect_quorum replicas (currently, it's true only in case of initial configuration; replication reconfiguration case will be fixed in the scope of #3427). If replication_sync_lag happens to be smaller than the network latency, box.cfg() will never return, neither can it be cancelled. We should probably introduce a new option box.cfg.replication_sync_timeout and make box.cfg() raise an error or leave the server in the 'orphan' state if it failed to sync within the specified timeout.

[locker]

Fixed by ca9fc33