Remove .bowerrc

If there are no further comments or suggestions for #2386 then I think it would be good to get this in. Remove .bowerrc from base repo but allows it to still be used for people with specialised dev environments by adding to .gitignore
Merge pull request #2407 from JohnONolan/no-bowerrc

Remove .bowerrc
Refactor the Ghost Editor

issue #2385, issue #2108

- Separate out the various objects which form the editor into their own
  modules
- Decouple the modules where possible
- Rename and reshuffle bits of modules for consistency
- Minimise public APIs of the modules, and ensure they are consistent
- Add comments to the modules
Upgrade CodeMirror

closes #2108

- upgrade to 4.0.1
- requires removing the deprecated setLine method