Handle csv uploads with CR and CRLF newlines

@maxfliri
Test parse_csv with the stream type used by Flask uploads

@maxfliri
Better implementation of lines generator

- Preserves correct handling of newlines in quoted values
- Avoids reading the whole input stream in memory

@maxfliri
Remove rogue print statement

@maxfliri
Merge pull request #109 from alphagov/cross-platform-newlines-for-csv-upload

Cross platform newlines for csv upload