Add pypy, pypy3, 3.2 but allow pypy3 and 3.2 to fail

Some Python environments are missing from the CI, so add them:

 * PyPy
 * PyPy3
 * Python 3.2

However, there's a problem with pypy3 and 3.2 at the moment (https://github.com/mahmoudimus/nose-timer/issues/51) so allow them to fail until a fix is found.