Allow a release to be zipped

Hey,

I created functionality for deploying. This makes it possible to automatically tar/zip releases, other than the current. This potentially saves a lot of space on the host.

To activate, add the following in your config under 'releases':
- compressreleases: true

Also, this fixes a bug in the TarGz task, introduced in the last commit. This resulted in the SCP command to be executed 3 times, twice on the server.