Fix: Basic webpack 4 support (styleguidist#849)

To have webpack 4 configured correctly we need to set the webpack mode.

Fix: Use editorConFfig.theme for CodeMirror theme (styleguidist#814)

Fixes styleguidist#788 by using `editorConfig.theme` in the config.  A fallback
for using the old `highlightTheme` option is already present in the
config schema.

Fix: Up Buble version to 0.19.2 (styleguidist#815)

Fixes styleguidist#807
Related styleguidist#798 styleguidist#764

Fix: Include filepath in props to Section/ReactComponentRenderer (sty…

…leguidist#803)

Fix: Decrease Buble version to fix wrong HTML entities encoding (styl…

…eguidist#801)

Fix: Update uglifyjs-webpack-plugin (styleguidist#797)

Close styleguidist#783

Chore: Remove semantic-release-tamia from package.json to use the lat…

…est version on Travis

Chore: Tweak deps

Fix: Inherit color (styleguidist#652) (close styleguidist#656)

Fix: Remove unused dependency (styleguidist#655)