Add logging to encryptor class
Add logging to encryptor class

Make it really easy for encryptors to log sensibly. These were in
the gpg encryptor but really belong in the base class.

Also refactored the plugin_classname for reuse.

TomPoulton/hiera-eyaml,charneykaye/hiera-eyaml,mkulke/hiera-eyaml,gdubicki/hiera-eyaml,TomPoulton/hiera-eyaml,elyscape/hiera-eyaml,gdubicki/hiera-eyaml,mkulke/hiera-eyaml,elyscape/hiera-eyaml,kyledecot/hiera-eyaml,charneykaye/hiera-eyaml,kyledecot/hiera-eyaml