HDF5 update to 1.8.10-patch1

HDF5 has released an update to 1.8.10-patch1. Just changing the download link and the sha1 seem  to perform correctly. 
This is my first pull request to the homebrew. There is a dupe at http://gh.codehum.com/mxcl/homebrew/pull/17244 , yet it hasn't been accepted.