Add Date class
Merge pull request #72 from chen3feng/develop

Add Date class
Add Bitmap and BloomFilter and adjust hash interface
Cpplint
Cpplint
Merge pull request #73 from chen3feng/develop

Add Bitmap and BloomFilter and adjust hash interface
Fix style
Merge pull request #74 from chen3feng/develop

Fix style
Fix test
Merge pull request #75 from chen3feng/develop

Fix test
Merge remote-tracking branch 'chen3feng/master'
add varint encoding