feat(githubprovider): The contentCtrl add now the github user and repository to static file urls
feat(staticfiles): githubUrlBuilder supports now a method to build url for static files, tests written
refact(githubContentProvider): changed the order of the parameters for githubUrlBuilder.buildSearchUrl
feat(staticfiles): added the method fetchStaticFile to the githubContentProvider
feat(staticfiles): refactored the staticfilerequesthandler

- moved the code to handle the request to pageStorageFS
- added the method fetchStaticFile to the gitContentProvider and use the
  new same method from pageStorageFS
- the staticfilerequesthandler is using now the provider to fetch the
  static file
- added a new route to app.js to handle the static file requests with
  github username and repository in the url

Closes #39