Add a trailing slash to dirwalker folder item paths
Add a blueprint for opening and caching URLs with `urllib2`_
Move the csvsource test source into a separate file
Move a test file into the tests directory
Add test description
Add csvsource option to take filename from an item key
Use expressions for csvsource fmtparams, allows whitespace delimiters
Make urlopener logging less verbose
Ignore generated docs
Add csvsource filename to yielded items when it comes from and item key