Local File System Storage Target: broken images and hyperlinks in HTML files

[carloposo]

Describe the bug
HTML files saved as backup do not show images and hyperlinks are broken because of wrong urls.

To Reproduce
Steps to reproduce the behaviour:
Make sure you have at least one page with embedded images and a link to another wiki page.

1. Go to Admin > Storage and select Local File System
2. Set the directory in the Target Configuration section
3. Click Apply button in top right corner
4. Scroll down the page and press Run in the "Dump all content to disk"
5. Open one of the HTML files just created
6. Images are not shown and links to other wiki pages are broken

Expected behaviour
Images are shown and links to other wiki pages work.

Host Info (please complete the following information):

• OS: OSX
• Wiki.js version: 2.0.0-rc.1
• Database engine: postgres 11