Check status of package dependencies during start.

Refs #3864
* Make sure that require() is able to resolve all dependencies
  listed in package.json.  If packages are missing halt the
  bootstrap process and display an error and help message for user.
I'd say it's probably safe to leave them in if you've tested in those three
major platforms.  It's really just a toss up between ugly with weird text
characters for the minority or ugly with no colors for the majority.  My
vote would be for the minority to have weird characters in that case.