Add stop method, refactor building cache keys.
Add stop method, refactor building cache keys.

raybuhr/grab,kevinlondon/grab,kevinlondon/grab,SpaceAppsXploration/grab,subeax/grab,shaunstanislaus/grab,raybuhr/grab,alihalabyah/grab,istinspring/grab,istinspring/grab,pombredanne/grab-1,liorvh/grab,maurobaraldi/grab,subeax/grab,subeax/grab,giserh/grab,alihalabyah/grab,giserh/grab,codevlabs/grab,DDShadoww/grab,pombredanne/grab-1,lorien/grab,SpaceAppsXploration/grab,DDShadoww/grab,huiyi1990/grab,liorvh/grab,huiyi1990/grab,codevlabs/grab,lorien/grab,maurobaraldi/grab,shaunstanislaus/grab