Improve error reporting slightly

* Removing the "e" from the end of raise shows the original stack trace, which provides us more information
* ".__name__" at the end removes unneeded clutter in the traceback printout
Remove empty entries, as they cause errors downstream
If an entry does a currency exchange it's balance won't be zero

* For instance, if I sold one currency and gained another, the balance value object will not sum to zero. This is a simple fix, but perhaps not the best way.
Fix quotes in setup.py