Always create metronome run dir
Always create metronome run dir

Metronome service fails to start with:

```
Jul 13 20:41:09 dcos-master-01234567-0 systemd[1]: Starting Jobs Service: DC/OS Metronome...
Jul 13 20:41:09 dcos-master-01234567-0 bootstrap[24433]: [INFO] Clearing proxy environment variables
Jul 13 20:41:09 dcos-master-01234567-0 bootstrap[24433]: [INFO] Expected cluster size: 1
Jul 13 20:41:09 dcos-master-01234567-0 bootstrap[24433]: [INFO] Waiting for ZooKeeper cluster to stabilize
Jul 13 20:41:09 dcos-master-01234567-0 bootstrap[24433]: [INFO] Starting new HTTP connection (1): 127.0.0.1
Jul 13 20:41:09 dcos-master-01234567-0 bootstrap[24433]: [INFO] Connecting to 127.0.0.1:2181
Jul 13 20:41:09 dcos-master-01234567-0 bootstrap[24433]: [INFO] Zookeeper connection established, state: CONNECTED
Jul 13 20:41:09 dcos-master-01234567-0 bootstrap[24433]: [DEBUG] bootstrapping dcos-metronome
Jul 13 20:41:09 dcos-master-01234567-0 bash[24445]: /bin/bash: /run/dcos/etc/metronome/service.env: No such file or directory
```

Fix by ensuring the run state directory always exists.

lingmann/dcos,asridharan/dcos,asridharan/dcos,amitaekbote/dcos,lingmann/dcos,branden/dcos,xinxian0458/dcos,BenWhitehead/dcos,branden/dcos,vishnu2kmohan/dcos,vishnu2kmohan/dcos,lingmann/dcos,darkonie/dcos,asridharan/dcos,xinxian0458/dcos,darkonie/dcos,dcos/dcos,asridharan/dcos,mellenburg/dcos,darkonie/dcos,xinxian0458/dcos,GoelDeepak/dcos,darkonie/dcos,amitaekbote/dcos,GoelDeepak/dcos,surdy/dcos,darkonie/dcos,jeid64/dcos,amitaekbote/dcos,jeid64/dcos,surdy/dcos,amitaekbote/dcos,mesosphere-mergebot/dcos,vishnu2kmohan/dcos,BenWhitehead/dcos,BenWhitehead/dcos,mellenburg/dcos,mesosphere-mergebot/mergebot-test-dcos,GoelDeepak/dcos,mnaboka/dcos,dcos/dcos,BenWhitehead/dcos,mesosphere-mergebot/dcos,jeid64/dcos,mellenburg/dcos,lingmann/dcos,kensipe/dcos,branden/dcos,kensipe/dcos,mesosphere-mergebot/dcos,surdy/dcos,xinxian0458/dcos,branden/dcos,mesosphere-mergebot/mergebot-test-dcos,mesosphere-mergebot/dcos,mesosphere-mergebot/mergebot-test-dcos,vishnu2kmohan/dcos,surdy/dcos,kensipe/dcos,mesosphere-mergebot/mergebot-test-dcos,mnaboka/dcos,dcos/dcos,mellenburg/dcos,mnaboka/dcos,mnaboka/dcos,GoelDeepak/dcos,jeid64/dcos,mnaboka/dcos,kensipe/dcos,dcos/dcos,dcos/dcos