Py2/3 Compatibility and Bug Fixes in dump/load for PriorityQueue

[ghost]

-Refactored both qr.py and test/tests.py to be py2/3 compatible with package futurize -Fixed bug in dump() where a 0 value was not allowing the loop to continue and popped with scores to put in the file object -Fixed bug in load() where the loaded values were not being packed before put in Redis

-Fixes Issue #9