Updates

• Fancy logging; webpack-log is now used for logging to the terminal (webpack-dev-middleware was already using this).
• The logLevel option is added for more fine-grained control over the logging.

Bugfixes

• MultiCompiler was broken with webpack 4.
• Fix deprecation warnings caused by webpack 4. Note that you will still see some deprecation warnings because webpack-dev-middleware has not been updated yet.