some issues with code including python versions

[shoaib-intro]

1. doc needs to convert into string to proceed further for re
   doc = str(doc).lower() # convert into string to handle error if input is else

2. while converting into binary from md5 encoding required to mention
   h = bin(int(md5(token.encode('utf-8')).hexdigest(), 16)) # to handle encoding error

3. Python version update to call dictionary items in 3.0
   for _, token in token_dict.items(): # instead of iteritems() in python version 2.0 replaced with items() in python 3.0

if __name__ == '__main__':
    # Just for demonstration
    doc = data # {doc_id, doc}
    binary_hash = simhash(doc)
    print(binary_hash)

[memosstilvi]

Hello @shoaib-intro. I am happy to review and merge a PR if you want to port the library to python 3.