We've introduced a regression in 6d75a4c6c4 where running
`embark run` breaks due to webserver options not being defined.
The reason this happened is because in the mentioned commit, we're checking given
webserver options with an identity check against `null` and only set dedicated
options, if that condition is true.
E.g.:
```
if (options.runWebserver !== null) {
webServerConfig.enabled = options.runWebserver;
}
```
Unfortunately, due to one of JavaScript design flaws, this condition behaves totally
different when no identity check is done, which causes Embark to break.
Meaning that in JavaScript:
```
undefined != null // false
undefined !== null // true
```
In other words, after the mentioned commit, the condition is true, resulting
in several webserver configurations to be set to `undefined`.
This conflicts at runtime when we compose webserver configurations out of user input
and Embark's defaults here: dc5de7c1b4/lib/core/config.js (L392)
In other words, since webserver config options are already set to `undefined`,
they don't get overridden by our config algorithm.
This commit ensures that webserver config values are not set when their values
are either `null` or `undefined`.
df2aa30fb4