Offer to install missing imports

[callumlocke]

If the uncaughtException handler receives a 'module not found' error, and it's for an node_modules package (i.e. string does not start with ../ or ./ or /)... the script should still exit with code 1, but then esbox should offer to install the missing dep.

• user can type i Enter to do npm install NAME
• or s Enter for npm install --save NAME
• or d Enter for npm install --save-dev NAME

and if there's no package.json, and the user chooses to save or save-dev, esbox should first create a package.json file containing {} before running the command.

[developit]

Just a +1 for this - similar to how esnextb.in detects dependencies using browser-module-sandbox, which is using detective under the hood.