Bitcoin address check by Gavin Andresen, public domain

https://bitcointalk.org/index.php?topic=1026.0

This will remove dependency on python-bitcoinaddress-0.2.2.tar.gz
package that conflicts with recent setuptools (issue #2867)
utils.bitcoin: Add header and make Django form optional
utils.bitcoin: Replaced pycrypto dependency with hashlib
utils.bitcoin: Add validate() function for API compatibility

This function was provided by python-bitcoinaddress-0.2.2.tar.gz
utils.bitcoin: Add self-tests using external dataset

This uncovers that not all invalid addresses are detected,
which is also a problem with python-bitcoinaddress-0.2.2.tar.gz
bitcoin.utils: Add command line interface for checking hashes
bitcoin.utils: Add the rest of testcase with valid hashes