Making npm install verbose

[NickBusey]

I had some trouble with some npm packages not installing, this makes that easier to spot. I don't really see a reason not to set it to verbose.

[gustawdaniel]

Hi. I have very similar issue to your and added verbosity to line 36 some months ago.

https://github.com/jshimko/meteor-launchpad/commit/b9a2eed2f9cdfd4f2a69c811a6ce29c331bcf2b4

What @NickBusey and @jshimko think about flag VERBOSE in launchpad.config or VERBOSE_BUNDLE VERBOSE_SOURCE

Now I think this verbosity is not necessary in most cases but it could be configurable.