BLD/TST/DEV: update tox to use python 3.4
- now installs any optional dep not relying on numpy for better local test coverage
- you can now pass arguments that will go to nosetests (e.g., for running network tests)
- removed tox_prll.ini because you can `pip install detox` and it will automatically build run and test across the configuration in tox.ini

@jreback you ok with this? just a bit of pruning ...
 seems ok
not that I use tox 
 ok ... it's useful for not having 5 different virtualenvs when you want to test
