Simplify input_files filenames

Don't define filename on input_files. New version or rbm uses the
project's filename if it is not defined in the input_file.

We rename the var/dest_filename options to filename to allow that.
Add keyring/mikeperry.gpg
Add libgcrypt
rbm.conf: add targets config for various platforms we'll support
Use osname rather than arch in filenames
tor-messenger: use osname in output filename
Add .gitignore