Check in sample .cloudkeychain file from agilebits
mostly-working support for cloudkeychain key derivation
more reorganization
fix some bugs... integration tests still don't work
Use pycrypto's pbkdf2 instead of pbkdf2's pbkdf2
more work
more cleanups; tests still do not pass
feedback from agilebits
so, the overview key I decrypt is correct... but hmacs don't work
All right! The HMAC now works! Back to feature dev!
add example datafile in agilekeychain format, tidy up integration tests
Initial cloudkeychain support

Merged from branch cloudkeychain
Integration tests for agilekeychain format

Merged from branch integration_agilekeychain