add sha1 , add some comments for MD5
add new line for BUILD
add crc32
port skiplist /random / erena  from leveldb/re2
add lzo algorithm for block compression
fix comments of chen3feng
add empty line at file end
add empty line at file end
cpplint all
delete chinese comments or change to english, comment out a test case for http_client
Merge pull request #99 from yeshunping/master

add sha1 , add some comments for MD5