Make manifest and root paths configurable

[zalox]

Hi,

I would like the opportunity to not use the cache directory for the manifest paths, please consider this change :)

[zalox]

This addresses #46 in some sense to.

[mariusbalcytis]

manifest_file_path should be configurable for that, I agree. Could you explain if there is a need for other parameters to be configurable in your case? As they are more like bundle internals (temporary files) and should not make such difference under normal circumstances.

[zalox]

Hi, Thank you for your quick reply! I would agree that manifest_file_path is the most useful one!

Scenarios where the others would be useful to move:

• root_directory : If you would like to put your package.json in some suitable directory for your build. For instance, you might have two projects in your build with a different package.json
• webpack_entry_config_path If you would like to provide your own configuration path. It might be useful for debugging, testing of new configurations or if you don't want to do your environment configuration in javascript.

The json file I'm uncertain of what it does, is it useful for the dev-server?