FT-556 add snappy compress method
add google snappy to tokuft and the test results as follows:
TOKU_ZLIB_METHOD Time=0.602126s , Ratio=0.33[8416782/25183377]
TOKU_ZLIB_WITHOUT_CHECKSUM_METHOD Time=0.559529s, Ratio=0.33[8415541/25183377]
TOKU_QUICKLZ_METHOD Time=1.079200s, Ratio=0.35[8743582/25183377]
TOKU_LZMA_METHOD Time=3.001958s, Ratio=0.33[8415141/25183377]
TOKU_SNAPPY_METHOD Time=0.171223s, Ratio=0.36[9184871/25183377]
FT-556 snappy 1.1.2
Change snappy version to https://github.com/google/snappy
Add snappy build to TokuThirdParty.cmake
Merge pull request #273 from BohuTANG/feature_snappy_FT556

Feature snappy ft556