Delete the orphan blocks while initialize WorkerStorage

The intializeWorkerStorage tries add allfoundBlock files during the registering. But if the meta data of certain files are missing or deleted, it will throw out some Runtime exception, which blocks the Worker from starting up. 
I wonder if it is possible to delete those orphan block files( what has been implemented in this PR).

OR alternatively,  we can move those orphan block files to some other places (in case the end user needs them later). Any idea?