Components defined with relative paths are not resolved correctly

[alj1s]

This issue seems to have been introduced in 4.0.

Setup: Specify a array of components in config file by path relative to config folder:

  components: function() {
    return ['./lib/components/Button/Button.js'];
  },

Expected: styleguide runs successfully.
Actual: npm run styleguide-server fails with errors:

ERROR in .//react-styleguidist/loaders/styleguide.loader.js!.//react-styleguidist/src/index.js
Module not found: Error: Cannot resolve 'file' or 'directory' ./lib/components/Button/Button.js in /Users/andrewjones/code/react-styleguidist-example/node_modules/react-styleguidist/src
@ .//react-styleguidist/loaders/styleguide.loader.js!.//react-styleguidist/src/index.js 5:10-54

ERROR in .//react-styleguidist/loaders/styleguide.loader.js!.//react-styleguidist/src/index.js
Module not found: Error: Cannot resolve 'file' or 'directory' ./lib/components/Button/Button.js in /Users/andrewjones/code/react-styleguidist-example/node_modules/react-styleguidist/src
@ .//react-styleguidist/loaders/styleguide.loader.js!.//react-styleguidist/src/index.js 6:9-61

See here for repro: https://github.com/ximenean/react-styleguidist-example
Downgrading styleguidist to v3 works as expected.

[alj1s]

Fast work! Thanks.