Support devserver

[MuhammadDicky]

It will be nice if this plugin can support webpack devserver watch.

[heppa]

Dear all, first of all many thanks for this awesome plugin...

To give a little bit more information on this topic, as I would also love to see this:
I am using the plugin to concatenate several configurations as I use one code base to generate different product bundles that are configured via a default configuration and a special configuration (application configuration, not webpack configuration).

I would be happy to see that the file is reconcatenated when one of the source files changed => that means, it should be possible to tell webpack to add the source files to the watches instead of the concatenated one.