Add a devserver example that uses node_modules

[appsforartists]

It's a very common workflow to import external open-source modules into a project being served by a devserver; therefore, the example should include it. Specifically, we should document whatever needs to be done in ts_library to make ts_devserver concat-and-serve node_modules.

According to the NPM homepage, lodash and react are 2 of the most depended-upon packages. At least one of them should be used in an example. Plus, both have external typings, so they would also showcase the need to include @types/react alongside react (#125).

Related: #103

[alexeagle]

Let's use #103 for this.