Remove S3funnel from mapreduce code
Merge branch 'master' into remove_s3funnel_from_mapreduce
Merge branch 'master' into remove_s3funnel_from_mapreduce
Pass through AWS credentials if available.
Handle rename across devices.
Merge branch 'master' into remove_s3funnel_from_mapreduce
Choose your own reduce separators, add setup_reduce function

Make the field and record separators into fields so that MR jobs can specify
their own without having to post-process.  This lets us output CSV instead of
tab-separated output.

A `setup_reduce(context)` function is also added to allow jobs to do any
required pre-reduce setup.
Removed a superfluous "not None" check.
Bail (nicely) if we don't match any input files
Add an error message if we fail to fetch remotes.