Added storage access time watching feature
Merge pull request #46 from yayugu/feature/time_watcher

Added storage access time watching feature
Replication over clusters
Fix the review inducation and make more tests
Fix a bug of cluster replication
Fix cluster replication issues
Refactor test of cluster replication
Fix namespace of boost for cluster replication
Fix cluster replication tests
Lock cluster::get_node_partition_map_size()
Fix test failure on Travis