Currently we need to check unit test results by opening console.html.
HTML reports would be nice for this purpose.
Note that the infra CI post script stores '*nose_results.html',
so the filenames need to end with 'nose_results.html'.
--with-html-output option is not available for python 3. I am not sure
the reason at now, but I think it is worth enabling it for python 2.
Change-Id: Icea8d21d0cf93f99f577e6609e9ced166a55609a
65951cf1b9