ScyllaDB release: version 1.2.2

ScyllaDB version 1.2.2, released in July 2016, is a bugfix update for the 1.2 stable branch, maintaining backward compatibility and supporting rolling upgrades. The release addresses several issues, including a problem with nested types that led to invalid types when queried, a race condition in Seastar causing crashes, memory over-allocation errors, and the creation of unnecessary table directories upon restart. The update also fixes a regression that slowed down performance on multi-core machines and resolves high read backlog issues leading to out-of-memory errors. Contributions from Avi Kivity and others include various bug fixes and performance improvements, such as better handling of user-defined type metadata and more conservative memory allocation for queued reads.