Ubuntu15 and systemd support

[justin8]

Added support for systemd systems with pip installs (Fedora 14+, RHEL 7+, Debian 8+, Ubuntu 15.04+ & Archlinux)

Added rspec tests for the service files.

Fixed collector paths for ubuntu pip installs (they go to /usr/local/share instead of /usr/share like most other OSes).

Fixed spec tests that had osfamily => 'Ubuntu'. Should've been osfamily => 'Debian', operatingsystem => 'Ubuntu' like on real systems.

[purplexa]

I don't see why any of this is necessary, personally, except maybe the spec test fixes for Ubuntu.

[justin8]

It adds support for pure systemd implementations like Arch Linux as well.

[purplexa]

If all you need is the unit file, why not try to get that straight into upstream?

[justin8]

I wrote it a while ago, and don't actually use diamond any more. Mostly because the upstream was too slow to do anything.

Also that would be one of the 9 files changed in the PR.

[jtriley]

Turns out the reason the service file is missing is because pip by default installs using binaries/wheels. The diamond wheel was built on ubuntu so when setup.py was executed it only evaluated the 'ubuntu' case statement in setup.py for service files. You can disable this using:

$ pip install --no-binary :all: diamond

which will do a source install that invokes setup.py, correctly identifies the current system, and installs the service file accordingly.