Creates a md5 hash using every file in a given folder

md5folder.py

    #Returns the md5 hash for every file in folder 'folder', except if the
    #file is named 'md5' (because that means the folder already contains a md5
    #hash)
    def md5_for_folder(self,folder, block_size=128):
        md5 = hashlib.md5()

        for root, dirs, files in os.walk(os.path.join(folder)):
                for f in files:
                    if f!="md5":
                        fp = open(os.path.join(folder,f),'r')
                        #Add data for file f to md5 in 128 block size
                        try:
                            while True:
                                data = fp.read(block_size)
                                if not data:
                                    break
                                md5.update(data)
                        except:
                            traceback.print_exc(file=sys.stdout)
                        fp.close()

        return md5.hexdigest()