Added GnuPG key generation program.

  * Added gpg-key-generator, which creates a directory under the current
    directory named "gpg-keys", creates a batch script for GnuPG to take as
    input to the "$ gpg --batch --gen-key " command. The gpg-key-generator
    will also somewhat handle cleanup of it's created files, appending
    instructions to the current GnuPG batch file, and creation of N keypairs
    at a time. It will call gpg itself, after creating the batch file, and
    create the keypairs. Lastly it prints a set of basic instructions for
    adding a new user account in order to avoid inadvertent mistakes to an
    actual user's GnuPG keyring. Do "$ gpg-key-generator --help" for more
    info.
  * First batch of test keypairs for unittesting leap_mx is included. The
    default keys were created with username: Louis Lingg <blackhole@leap.se>,
    and the passphrase for each secret key is "leap" (no quotes).
Merge branch 'feature/gpg-keygen' into develop