Progress: Continue adding GPGME support.

Progress: Continue adding GPGME support.

I don't like a lot of things about GPGME, so do not enable it by default.

I'm still uncertain how I want to structure the encryption support with gpgme.
I plan on considering other encryption and checksum algorithms/libraries.

For now just create an encrypt send step file.
This is highly subject to change.

This adds a new header called "encrypt" that will explicitly designate the encryption method used.