Add support for Python 3.2, 3.3, 3.4

Builds, and all unit tests pass, on Python 2.6, 2.7, 3.2, 3.3, and 3.4.

I am working on updating Travis to test multiple Python versions. That could be included in this PR, or another one. What is your preference?

Note: on my Mavericks machine, this test fails under all Python versions, both before and after this patch series:

    =================================== FAILURES ===================================
    ____________ TestPixelFunc.test_ang2pix_nest_outofrange_doesntcrash ____________

    self = <healpy.test.test_pixelfunc.TestPixelFunc testMethod=test_ang2pix_nest_outofrange_doesntcrash>

        def test_ang2pix_nest_outofrange_doesntcrash(self):
            # ensure nside = 1 << 30 is incorrectly calcualted,
            # because Healpy_Base2 works upto 1<<29.
            # Healpy_Base2 shall not crash the test suite
            id = ang2pix(1<<30, self.theta0, self.phi0, nest=True)
            theta1, phi1 = pix2ang(1<<30, id, nest=True)
            self.assertFalse(np.all(np.isfinite(theta1)))
    >       self.assertFalse(np.all(np.isfinite(phi1)))
    E       AssertionError: True is not false

    test/test_pixelfunc.py:64: AssertionError
    ===================== 1 failed, 78 passed in 10.03 seconds =====================

However, I think that the best resolution here would be to have Healpy work with all pixel resolutions up to and including `nside=1<<30`.