Use the correct URL in the test

This saves loading a redirect in the test suite. speeeeeeed
Merge pull request #1797 from alex/patch-3

Use the correct URL in the test
Use base85 instead of base64 for the bundled pip
Merge pull request #1798 from dstufft/base85-get-pip

Use base85 instead of base64 for the bundled pip
Require an already created session to be passed into APIs