feat(*): shared volume support for controller/logger (adds store-metadata and store-volume)

This introduces **deis-store-metadata** and **deis-store-volume** as new components which run on all hosts. These enable controller and logger to mount a shared CephFS filesystem. 

**To-Dos**
- [x] Fix bugs
- [x] Ensure controller and logger work properly when using /data
- [x] Update store, controller, and logger tests
- [x] Update store, controller, and logger documentation (especially managing_deis sections)

closes #2041
closes #985