Make test pypi the default pip installer

It's possible to make the testpypi index the default for pip, but still retrieve any dependencies not on testpypi from the production repo. You just need a pip.conf like this:

$ mkdir ~/.pip
$ cat .pip/pip.conf 
[global]
index-url = https://testpypi.python.org/simple
extra-index-url = https://pypi.python.org/simple