Restructure to allow root entry and correct sub directory entry paths

We can now have a root entry point at the same time as having a sub directory entry points.

### Here are the highlights of the changes
* Fixes the relative paths to file loader assets no matter where the entry point is in the path
* An absolute path will be used for the `webpack-dev-server`
* Relative paths will be used if wanted by default in the `webpack` build into `/dist`
* A public relative path is setup in the entry point file rather than in the config now
* Added the boilerplate example with both one root and one sub directory entry point
* It will allow for any number of levels deep in the directory structure as long as you change the relative public path

### Notes:
I believe there should be a fix to the file-loader as in my fork here [talves/file-loader](https://github.com/talves/file-loader/compare/webpack:master...master) to make sure url paths end up in a more direct relative path to the index.html entry point. (i.e. images/... vs ../boilerplate/images/...) by using a root context (context + /boilerplate)
The change is not required, but allows us to have a stand alone entry path without having to be dependent on the public path in the file loader.  

In the current solution, we will not be able to export a module to just any path.  I feel this is unacceptable.