TST: TravisCI failures
It looks like Travis is failing to install the dependencies recently.

In `ci/install.sh`, we run

```
pip install $PIP_ARGS -r ci/requirements-${wheel_box}.txt
```

where `PIP_ARGS` (I think) is something like `-I --use-wheel --find-links=http://cache27diy-cpycloud.rhcloud.com/2.7/ --allow-external --allow-insecure
` depending on which version.

Which produces this error (sometimes):

``` python
Downloading/unpacking python-dateutil==2.1 (from -r ci/requirements-2.7.txt (line 1))
  http://cache27diy-cpycloud.rhcloud.com/2.7/ uses an insecure transport scheme (http). Consider using https if cache27diy-cpycloud.rhcloud.com has it available
  Downloading python_dateutil-2.1-py27-none-any.whl (unknown size): 118kB downloaded
Cleaning up...
Exception:
Traceback (most recent call last):
  File "/home/travis/virtualenv/python2.7_with_system_site_packages/local/lib/python2.7/site-packages/pip/basecommand.py", line 122, in main
    status = self.run(options, args)
  File "/home/travis/virtualenv/python2.7_with_system_site_packages/local/lib/python2.7/site-packages/pip/commands/install.py", line 274, in run
    requirement_set.prepare_files(finder, force_root_egg_info=self.bundle, bundle=self.bundle)
  File "/home/travis/virtualenv/python2.7_with_system_site_packages/local/lib/python2.7/site-packages/pip/req.py", line 1173, in prepare_files
    self.unpack_url(url, location, self.is_download)
  File "/home/travis/virtualenv/python2.7_with_system_site_packages/local/lib/python2.7/site-packages/pip/req.py", line 1320, in unpack_url
    retval = unpack_http_url(link, location, self.download_cache, self.download_dir, self.session)
  File "/home/travis/virtualenv/python2.7_with_system_site_packages/local/lib/python2.7/site-packages/pip/download.py", line 587, in unpack_http_url
    unpack_file(temp_location, location, content_type, link)
  File "/home/travis/virtualenv/python2.7_with_system_site_packages/local/lib/python2.7/site-packages/pip/util.py", line 621, in unpack_file
    unzip_file(filename, location, flatten=not filename.endswith(('.pybundle', '.whl')))
  File "/home/travis/virtualenv/python2.7_with_system_site_packages/local/lib/python2.7/site-packages/pip/util.py", line 491, in unzip_file
    zip = zipfile.ZipFile(zipfp)
  File "/usr/lib/python2.7/zipfile.py", line 714, in __init__
    self._GetContents()
  File "/usr/lib/python2.7/zipfile.py", line 748, in _GetContents
    self._RealGetContents()
  File "/usr/lib/python2.7/zipfile.py", line 763, in _RealGetContents
    raise BadZipfile, "File is not a zip file"
BadZipfile: File is not a zip file
```

I've reproduced this locally.

Can we verify that the wheels hosted at `cache27diy-cpycloud.rhcloud.com/2.7/` were built correctly? I'm guessing `cpcloud` refers to @cpcloud?
