These warnings are visible whenever you import scipy (or another package) that
was compiled against an older numpy than is installed.  For example compiled
against 1.5.1, like current scipy binaries are, and used with 1.7.0.

These warnings aren't useful; if numpy would really break its ABI it would be
noticed in no time without these warnings.

Travis recently upgraded to virtualenv 1.8, which has dropped support
for Python 2.4. So, in our Python 2.4 setup script, we need to
explicitly fetch and use virtualenv 1.7. Likewise for pip 1.1.

File imported from the already-fixed version for patsy:
  https://github.com/pydata/patsy/blob/0316d2901f4195db06e8091c15f37d9fe4ad09de/.travis-make-py24-virtualenv.sh

The problem was that in 32bit Ubuntu 12.04, one gets the following:

>
/home/njs/numpy/.tox/py27/local/lib/python2.7/site-packages/numpy/random/tests/test_random.py(363)test_pareto()
-> np.testing.assert_array_almost_equal(actual, desired, decimal=15)
(Pdb) actual[1, 0]
52828779.702948704
(Pdb) desired[1, 0]
52828779.702948518

and the test was comparing the numbers to 1e-14, which obviously
failed.

Fixes #424.

This should fix the problems with numpy.insert(), where the input values
were not checked for all scalar types and where values did not get inserted
properly, but got duplicated by default.