This adds a new "crypto" test script to the test suite to test
PGP/MIME signature verification and message decryption. Included here
is a test GNUPGHOME with a test secret key (passwordless), and test
for:
* signing/verification
* signing/verification with full owner trust
* verification with signer key unavailable
* encryption/decryption
* decryption failure with missing key
* encryption/decryption + signing/verfifying
* reply to encrypted message
* verification of signature from revoked key
These tests are not expected to pass now, but will as crypto
functionality is included.
