add mysqls into gitignore.
add mysqls into gitignore.

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