Add Mapper/Reducer
Merge pull request #1 from esong/mapper

adding mappers and reducers. thanks!
learning how string types work, fixing copies of mappers/reducers to fit the style
catching killall commands, fixing mapper/reducer copies again.
you can only run one instance at a time.
related to issue 2
Merge branch 'master' of github.com:3stan/ml
restructuring and adding retries