Major interal update, as well as a breaking change.  upload() has been
completely re-written, and now leverages Java 7 nio performance boosts.
More buffers have been added to ensure that memory is used prudently.
This means that users on a fast internet connection can mass upload
quickly with a multi-threaded bot without exceeding the default java
heap space (128mb).  Other fixes include documentation and some
usability updates.