Rugged for GollumRails

Adding my rugged implementation. 

works:

- [ ] page
  - [x] page creation
  - [x] page update
  - [x] page delete
  - [x] page links
- [x] file
  - [x] file create
  - [x] file delete
- [x] gollum-lib
  - [ ] all internal methods
Unused method argument - `try_on_disk`. If it's necessary, use `_` or `_try_on_disk` as an argument name to indicate that it won't be used.<br>Surrounding space missing in default value assignment.