Documented tough-cookie installation.
Correct repository url

It's https:// instead, though it would automatically redirect.
Merge pull request #935 from fritx/patch-1

Correct repository url
Merge pull request #884 from wbyoung/document-tough-cookie

Documented tough-cookie installation.
Add support for multipart form data via the options object
update README to include new option
form-data no longer an optional dependency