flag to allow input resolution to fallback to cwd

[thejmazz]

by default off, but can be useful for putting quick pipelines together.

else need to make sure files end up in DAG

[thejmazz]

For example, to get starting files from CWD into DAG:

const getters = task({
  input: {
    reference: '*.fna',
    reads: '*.fq'
  },
  output: [ 'reference.fna', 'reads.fq' ]
}, ({ input: { reference, reads } }) => `
cp ${reference} reference.fna && \
cp ${reads} reads.fq
`)