Rename "main" to "object-packer" and specify that file as the executable for the gem.
Specify library version and dependencies.
Ignore generated gem files.
Make sure to re-build if config file changes.
Load and run the project's rakefile from whatever the current working directory may be.

+ Can't change the working directory, because need to use user config file.
+ BUG: Currently loads the main library file twice. Not sure why.
Load config file in executable, and pass command line arguments to Rake.