Start the FastBoot server immediately when --build=false

[treywood]

Going through the User Guide, I noticed that using the suggested command for debugging:

$ ember build && node --debug-brk ./node_modules/.bin/ember fastboot --no-build

would never start the server. After poking around I found that $ ember fastboot --no-build would start and immediately exit since no 'postBuild' event is fired to start the server. The changes in this PR cause the server to start immediately when --build=false

[tomdale]

@treywood Hey, thanks for the PR!

We discussed this PR on the call today. I am a little leery about accepting this patch as-is. There is some work on-going to give addons the ability to patch into the built-in Ember Express server. That seems like a better option than hard-coding in special case behavior about the build into the server. (IMO the server already shouldn't have any knowledge of the build system, and I don't want to canonize that bad architectural system by building on it further.)

That said, I think I would be OK accepting a PR in the interim if there was a different event than postBuild that we could listen for that was triggered whether or not the build was kicked off—although I'm not sure if such a thing exists. But I'm not comfortable with the server starting to parse build-specific CLI options.

[simonihmig]

Just found this by coincidence. Submitted a PR for that issue recently that was already merged: #346. Should be able to close this then!

[rwjblue]

Dang, I'm sorry about missing this PR originally @treywood.