refactor options for db
refactor options for db

move getOptions() into closure -> we can remove the this._options parameter

remove options variable from methods, use parameter instead
this is safe since we always create a new object and extend it

timkuijsten/levelup,toddself/levelup,Level/levelup,JTKnox91/levelup,timkuijsten/levelup,toddself/levelup,roppa/levelup,lastguest/levelup,JTKnox91/levelup,djchie/levelup,roppa/levelup,djchie/levelup,lastguest/levelup