Workflows: add CWL support

[sb10]

Implement "proper" workflows by adding CWL support, which would parse the CWL and resolve it down in to the existing way of adding commands with dependencies.

Possibly useful: https://github.com/robertkrimen/otto javascript in go https://github.com/sbinet/go-python python bindings in go http://spikeekips.tumblr.com/post/97743913387/embedding-python-in-golang-part-2 example of above being used (https://github.com/spikeekips/embedding-python-in-golang)

https://github.com/MG-RAST/AWE is written in go and has cwl support? CWL webpage points to this fork as having alpha cwl support: https://github.com/wgerlach/AWE, specifically https://github.com/wgerlach/AWE/tree/master/lib/core/cwl

You can test conformance of a cwl runner with: https://github.com/common-workflow-language/cwltest

Example workflows: https://github.com/common-workflow-language/workflows/ I have this cloned to ~/src/git/cwl-example-workflows

[sb10]

Foundational work for this is on-going on the develop branch of https://github.com/sb10/cwl.go