Improve naive bayes unit test.
Add predict_storage method to the Fitter base class.

And minor code improvements.
Fix error string formatting.
BayesStorage fixes and update.
Use predict_storage for input of type Instance.
Improved naive bayes and removed sklearn version.
Fix unit tests.
Default implementation of predict with predict_storage.
Merge pull request #73 from lanzagar/bayes

Implementation of Naive Bayes, which works on Table and SqlTable data.