made upload.S3Uploader more encapsulated, added methods for file retrieval etc
upload.Localuploader now more-or-less working
upload.DropboxUploader should work
Added date parse function

Takes a bunch of text, looks for dates and returns the most common one
and the number of times it occured.
Intended to be used with document classes to specifiy the date of the
documents.
Cleanup from merge
Merge pull request #3 from staffanm/feature/local-storage

Alternate storage backends (https://github.com/staffanm)
link to list of contributors
Add empty base class for documet extractors
Use base class for all document classes
fetch date
.
make document classes follow the same standard