Base a new docker file off of node:8-alpine seems to work well with newer sass versions which was an issue with the older alpine images. Adding in python for gyp to work and --unsafe-perm because npm was complaining a lot about it.
Fixing issues with running `sourcey/spectacle` docker file generating below errors:
```TypeError: Cannot read property '$ref' of null
at replaceRefs (/usr/local/lib/node_modules/spectacle-docs/app/lib/resolve-references.js:169:11)
at replaceRefs (/usr/local/lib/node_modules/spectacle-docs/app/lib/resolve-references.js:189:5)```
