SCHEMA-130. Use generics in CellDecoderFactories.

Signed-off-by: Aaron Kimball <aaron@wibidata.com>
SCHEMA-231. Move general methods in LsTool to ToolsUtil in preparation for GetTool and ScanTool.
SCHEMA-140. Clean up avro definition of MetaTableBackup.

Signed-off-by: Milo <milo@wibidata.com>