scipipe/scipipe: v0.9.4: New ParamCombiner component and Important fix for a deadlock bug

This release contains important improvements and bugfixes kindly contributed by @dwmunster:

• A new ParamCombinator component.
• Improved temp dir, hashing more information for tasks, such as full path (not just the basename), and values of params and tags.
• Fixes an important bug that could cause deadlocks in some cases. See #81 for mroe info.

On a smaller note, the CircleCI configuration is now updated to their new 2.0 syntax.

Upgrade is highly recommended, as usual with:

go get github.com/scipipe/scipipe/...