before you execute file, please close it - not no get 'Text file busy'
Merge pull request #18 from ministryofjustice/fix-shaker-file-close

before you execute file, please close it - not no get 'Text file busy'
COTTON_CONFIG
Merge pull request #19 from ministryofjustice/env-config

Look for precense of COTTON_CONFIG environment variable and use, falling back to  ~/.cotton.yaml
Raise exception rather than using abort