Check for the Resource dir before building

This is the first commit of a series in this pull request. Please don't merge anything until the checklist is complete AND you're happy with the commits. :wink: 

What I plan to do, please comment and improve thi list as you want :
- [ ] Check all the fs calls
  - [X] The Resource directory could be omitted
  - [ ] validate that nothing else can be absent
- [ ] use promises for handling errors and callbacks (with [bluebird](https://github.com/petkaantonov/bluebird/blob/master/API.md#promisification))