Make the PIP install instructions clearer

[mnealer]

Can you make the name change for the pypy version a little more obvious. I spent ages before I found that tiny line buried in the readme. It should be made clear in a PROPER pypy pip install sections, not an 'oh yeh we changed the name for pip' right at the end of the install instructions

[keszybz]

Hmm, the "Installation" section seems pretty clear to me. If you think you can improve it, please submit a pull request.

[Guiorgy]

@keszybz the The project is also available on pypi as systemd-python. line is under the To build from source heading, which I assume is the main cause of confusion. I'd expect the line to be under the Installation at least.

EDIT: Also, it'd help to have a pypi badge that links directly to the pypi page without the need to search for it manually.

EDIT2: The Build Status badge seems broken (404), you might want to look into that

[Guiorgy]

@mnealer, is the current format satisfactory?