Remove unnecessary empty line
Add Digest and Digest::SHA as optional dep
I#1 - Recommends Crypt::OpenPGP

And since that depends on Math::Pari through Crypt::Random, but the
author/maint is totally unresponsive for patches/PR, then lets
just recommend it as well.

https://github.com/wreis/DBIx-Class-EncodedColumn/issues/1