Add API option to suppress console output

[malept]

Initially from @anulman in #108:

Option to suppress console output: ember-electron should be able to provide its own messaging to the end user; comments about "converting CLI / grunt / etc scripts yourself" and preload script handling are inaccurate given our use (relevant source)

This should ultimately be a common option in all of the API endpoints.

Similar PR (but for Packager): electron/packager#541

[MarshallOfSound]

@malept Is this separate to the interactive flag or do we just need to make console.log and such follow the interactive setting?

[malept]

@MarshallOfSound I'd have to see how we use interactive all over, but that may well be the case.

[anulman]

If we're looking at this as coupled with interactive, what do you think of moving the api-level interactive code up to the command layer (i.e. electron-forge-import.js vs api/import.js)?

From what I've read in api/start and api/import, it seems you use interactive to prepare options for the build tools beneath. Could it be considered the native / default consumer of the api fns?

Very curious what you think. I'm still getting familiar with Forge's nooks & boundaries :)