Use python-systemd as the name

We want the package to be installed under this name.
This is also used for sdist, and we want python-systemd-<version>.tar.xz.

Author: keszybz

setup.py

@@ -30,7 +30,7 @@
                      sources = ['systemd/login.c',
                                 'systemd/pyutil.c',
                                 'systemd/strv.c'])
-setup (name = 'systemd',
+setup (name = 'python-systemd',
        version = version,
        description = 'Native interface to the facilities of systemd',
        author_email = '[email protected]',