Rewrite gzip.inflate and gzip.deflate as Process1

This PR closes #130. The new `deflate` and `inflate` functions are very similar to the old ones. Both contain a collect function that collects as many chunks as available from the de- and inflater.

I also decided to remove `gunzip` in this PR because of the following reasons:
 - it has zero tests and based on the complexity of its implementation I consider it buggy
 - it is a bad example for this library. This should not be the way how to write processes with scalaz-stream.
 - it is tied to the representation of `Process` and this should not be the case for something like `gunzip`. You would also need to change it when you want to do the `Process` refactoring

If you want to keep `gunzip` as it is now, just close this PR.