Current implementation on task definition by the user is somehow javascript dependent.
Example:

const gunzipIt = task({
    input: '*_genomic.fna.gz',
    output: '*.fa',
    params: { output: 'uncompressed.fa' }
  }, ({ params, input}) => `gunzip -c ${input} > ${params.output}`
)

It would be nice to abstract the user from this object, function task shape, to something more user-friendly. For example:

const gunzipIt = { task:
  { input:  '*_genomic.fna.gz',
    output: 'uncompressed.fa',
    function: '`gunzip -c ${input} > ${params.output}`'
  }
}

Notice that I removed params.output, because that can be tricky for the user to understand, and instead this check of the output pattern could be done by the api.
This could be integrated with #74 .