Added CREATE DATABASE statement to sql script.
Added CREATE DATABASE statement to sql script.

schema.sql assumes that database is already created in MySQL which is not always the case.

SteamShon/incubator-s2graph,SteamShon/incubator-s2graph,jongwook/incubator-s2graph,daewon/incubator-s2graph,jongwook/incubator-s2graph,SteamShon/incubator-s2graph,daewon/incubator-s2graph