Fixes #118

Briefly I've done following things:
- add compression options in TitanCFOptions
- set flags in header when there is compression dictionary
- add some members(states, sample data, etc.) in BlobFileBuilder for dictionary compression logic
- write the dictionary in meta blocks, when dictionary compression is enabled
- refactor BlobEncoder to support dictionary update

currently for decoding
- update BlobFileReader and BlobFileIterator to return Status::NotSupported if a blob file come with dictionary compression.
- add a test case for BlobFileReader

Issue Number: https://github.com/tikv/tikv/issues/8635Signed-off-by: hexyoungs <chuxdesign@hotmail.com>