feat(systemd): save systemd file to /etc/systemd, not /lib/systemd

closes TryGhost#414
- change location to /etc/systemd/system
- ensure uninstall will delete from either location

extensions/systemd/index.js

@@ -33,7 +33,7 @@ class SystemdExtension extends cli.Extension {
             user: uid,
             environment: this.system.environment,
             ghost_exec_path: process.argv.slice(0,2).join(' ')
-        }), 'systemd service', serviceFilename, '/lib/systemd/system').then((generated) => {
+        }), 'systemd service', serviceFilename, '/etc/systemd/system').then((generated) => {
             if (!generated) {
                 this.ui.log('Systemd unit file not generated', 'yellow');
                 return;
@@ -49,12 +49,17 @@ class SystemdExtension extends cli.Extension {
             return;
         }
 
-        let serviceFilename = `/lib/systemd/system/ghost_${instance.name}.service`;
+        let serviceFilename = `/etc/systemd/system/ghost_${instance.name}.service`;
+        let oldServiceFilename = `/lib/systemd/system/ghost_${instance.name}.service`;
 
         if (fs.existsSync(serviceFilename)) {
             return this.ui.sudo(`rm ${serviceFilename}`).catch(
                 () => Promise.reject(new cli.errors.SystemError('Systemd service file link could not be removed, you will need to do this manually.'))
             );
+        } else if (fs.existsSync(oldServiceFilename)) {
+            return this.ui.sudo(`rm ${oldServiceFilename}`).catch(
+                () => Promise.reject(new cli.errors.SystemError('Systemd service file link could not be removed, you will need to do this manually.'))
+            );
         }
     }
 }