Revert to previous md5 as on PyPI

The md5 checksum of the file on PyPI seems to now have the previous value in commit 1bc08df95e and not the value added in commit 071776f6ce.

Trying to use `conda build pymc` currently gives this error:
Error: MD5 mismatch: '03678068b552eecb16fc7aded39d125a' != '3b644a6e11cd2a57c6fcd3ee593d8d9e'
Merge pull request #75 from ihuston/patch-1

Revert to previous md5 as on PyPI