fixes the leveldb link
fixes the leveldb link

previously https://code.google.com/p/leveldb/ was linked, but the project was moved to https://github.com/google/leveldb
JTKnox91/levelup,djchie/levelup,timkuijsten/levelup,toddself/levelup,lastguest/levelup,JTKnox91/levelup,roppa/levelup,lastguest/levelup,djchie/levelup,toddself/levelup,timkuijsten/levelup,roppa/levelup,Level/levelup