BACKLOG-181 - Metastore MemoryMetaStore uses synchronized methods instead of a concurrent collection - added concurrent tests for MemoryMetaStore
BACKLOG-181 - Metastore MemoryMetaStore uses synchronized methods instead of a concurrent collection - added thread-safe implementation for MemoryMetaStore and fix some bugs
BACKLOG-181 - Metastore MemoryMetaStore uses synchronized methods instead of a concurrent collection - code refactoring according to Nick Baker's comment
Merge pull request #6 from MikhailGorbachev/BACKLOG-181

BACKLOG-181 Metastore MemoryMetaStore uses synchronized methods instead of a concurrent collection