Nans cause database failure

[mpharrigan]

sqlalchemy.exc.DataError: (raised as a result of Query-invoked autoflush; consider using a session.no_autoflush block if this flush is occurring prematurely) (DataError) 

(1264, "Out of range value for column 'mean_test_score' at row 1", None)
'UPDATE trials_v3 SET status=?, mean_test_score=?, mean_train_score=?, train_scores=?, test_scores=?, n_train_samples=?, n_test_samples=? WHERE trials_v3.id = ?'
('SUCCEEDED', nan, 5.9117118738995851, '[5.875094311095048, 5.964270097753747, 5.826748523773368, 5.970600009795744, 5.927208228433113]', '[NaN, 5.4756195605412055, -0.22265625, 5.674961419430565, 4.636925810916765]', '[33863, 33863, 36000, 33863, 33863]', '[40000, 40000, 37863, 40000, 40000]', 68)

This is with mysql. It would be nice if it could insert a nan instead of raising an exception

edit: added some line breaks to make it slightly more readable

[cxhernandez]

resolved in #110