Reorganize module a bit
Change encrypt and decrypt to encrypt_block and decrypt_block
Add encrypt and decrypt functions that work on arbitrary-length data
Add tests
Add camencrypt and camdecrypt scripts
Allow CamCrypt objects to be initialized from the constructor
Merge pull request #2 from gtback/updates

1. Make encrypt and decrypt work on arbitrary-length buffers, while renaming the original functions to encrypt_block and decrypt_block. This change is technically backwards-compatible, since encrypting a single 16-byte block should work the same regardless of which function you call; old code won't need to get modified, though if external code is splitting up longer buffers, it can now be simplified.
2. Add some unit tests.
3. Add command line scripts for encrypting and decrypting files from the command line. Run "camencrypt -h" or "camdecrypt -h" for a summary of the options.
4. Allow users to initialize the CamCrypt object directly from the constructor.
5. Raise a clearer error if keygen hasn't been called. Before, it would complain about self.bitlen not being defined.