Detailed diagnostic info on crash

[KidkArolis]

It's the most frustrating thing when a tool such as jetpack doesn't work, in dev locally, but especially in production where it's much harder to debug.

It shouldn't be hard to print out detailed debug info upon crash, e.g.

• all the config options it managed to collect
• current working dir
• whether client side code exists in location (easy to miss the build step for a number of reasons)
• whether jetpack.config.js exists
• the version of jetpack, node and npm

[KidkArolis]

Hopefully having simplified jetpack greatly will help with this!