Use int() instead of round() to cast float to int

Printing a float that has been rounded in python 2.* causes a ".0" to be
appended to the variable, whereas in python 3.*, the decimal place is
removed. This was causing the assertion in test_stats_format() of
test_stats.py to fail under python 2.7, as the expected string is:

    95% confidence values from 3 iterations:
    -0.48 2.0 4.48

Whereas the round() function in python 2.7 caused the returned string to
be:

    95.0% confidence values from 3 iterations:
    -0.48 2.0 4.48

This patch addresses this issue, so that the output is consistent on
both python 2.* and 3.*.