Merge pull request #11 from Memrise/master

Decode URLs properly before passing file path to S3
Add configurable result path
reuse boto connection in result storage
Merge pull request #12 from clifff/reuse_result_storage_connection

reuse boto connection in result storage
Ensure that root_path is joined as a directory
Path join requires os package
Merge pull request #13 from spiegela/master

Enable configuration result storage path