Removed dependency mapreduce.lib.files

[fcaldas]

Hi,

I am trying to use CloudStorageLineInputReader for inserting CSV files into datastore but it looks like one of the library dependencies were removed from mapreduce. I am getting the following error:

`
File "input_readers.py", line 26, in
from mapreduce.lib import files

ImportError: cannot import name files
`

The file input_reader.py is on the top level directory of my project, just where I copied the source of mapreduce.