Centos 6 and Upstart 0.6.5 support

Fixes #26 and #23 

Test report from CentOS 6.5:

```
[vagrant@localhost pleaserun]$ facter | grep operatingsystem
operatingsystem => CentOS
operatingsystemmajrelease => 6
operatingsystemrelease => 6.5
[vagrant@localhost pleaserun]$ sudo -E `which ruby` `which rspec`
................................*...*....................

Pending:
  PleaseRun::Platform::Launchd deployment cannot be attempted
    # platform is not darwin
    # ./spec./platform/launchd_spec.rb:38
  PleaseRun::Platform::Systemd deployment cannot be attempted
    # no 'systemctl' program found
    # ./spec./platform/systemd_spec.rb:43

Finished in 4.47 seconds
57 examples, 0 failures, 2 pending
```