filehash application (II): clean up the filehash database

Even though, filehash save your memory usage, you might still want to clean up the saved filehash-database from the hard driver because there is also the size limitation of the hard driver. Two ways to clean up the database created by filehash.

1. dbReorganize(db)

2. file.remove("dbname")

The first way just clean up the saved information in the db. The db is still exist. The file size of course is very small. The second way will delete db out from your hard driver.