Add's a test for the .write with no types caching bug
Add fix
Missing newline after merge
Add comment on why in the rich pipe
Review comments, comment on the IdentityFunction, make it an object. Few comments in the write method.
Merge pull request #913 from twitter/feature/tsvCacheBug

This handles the case where scalding will save out a tsv and re-use it down stream leading to issues where the types are not strings