Permalinks config option is not respected #484

<!-- Please don't delete this template or we'll close your issue -->

<!-- Before creating an issue please make sure you are using the latest version of Saber. -->

<!-- Issues which contain questions or support requests will be closed. -->

<!-- Please ask questions via following several ways. -->

<!-- https://chat.saber.land/ -->

<!-- https://stackoverflow.com/questions/ask?tags=saberjs -->

Bug report

Steps to reproduce

Clone this branch: https://github.com/andreasvirkus/cottage/tree/refactor/saber git clone git@github.com:andreasvirkus/cottage.git

1. Downgrade saber to 0.8.1 (since > 0.9 has #483)
2. Make sure you have page: /:slug in your saber.config.yml file

   permalinks:
   page: /:slug

3. Visit the local server and try to access the pages /about or /contact

What is expected?

Running saber should compile the dev bundle and start up the development server.

What is actually happening?

Saber returns the 404 page and you can only access those pages /about.html and /contact.html

Other relevant information

• Result of running saber -v: 0.8.1
• Is Saber a global or local install? local install
• Which package manager did you use for the install? npm
• Does this issue occur when all plugins are disabled? yes