Add unzip to toil workers and git to toil leader

[Jeltje]

To allow git clone toil-scripts and to be able to run rnaseq pipelines, which require unzip but don't check for it.

[hannes-ucsc]

Ok with unzip. But git pulls in a rats tail of other stuff. Is there any way we can avoid git?

[Jeltje]

Actually unzip is no longer needed. Git is apparently the new way to get the toil-scripts, so maybe there's another way to pull those in?

[hannes-ucsc]

How about cloning toil-scripts on the head node and rsyncing it over to the leader?

[Jeltje]

I'm just following John's instructions after finding myself unable to rsync a single script (the way we used to). It's all fine with me, but it would be good to agree on something and add the preferred method to the toil-script README.