lodash.merge module causes problems with Windows path length limitation

See this discussing for background: https://github.com/joyent/node/issues/6960

The lodash.merge module causes a very deep folder structure that gives problems in Windows. Filepaths can be no longer than 260 characters. 

As a result we are not able to use Nuget to package and deploy our NodeJS server due to this problem.
We don't actually need all of lodash so let's minimize our dependencies. Let's actually use the [object-assign](https://www.npmjs.org/package/object-assign) module and then have `assign = require('object-assign')` and then `engOpt = assign({}, DEF, engOpt)`.