fix bugs of dot in python

If there are no `transpose()` in `self.theta`, a

*ValueError: matrices are not aligned*

is occurring. The former test case just ignore this situation.

Author: Xusen Yin <yinxusen@gmail.com>

Closes #463 from yinxusen/python-naive-bayes and squashes the following commits:

fcbe3bc [Xusen Yin] fix bugs of dot in python