Better handle apps deployed from the wrong directory

[fiveisprime]

trafficstars

If a customer deploys an app that's nested in a subdirectory, warn them.

There are a couple of ways to check this:

• If deploying to node, prompt if package.json isn't found in the root
• If deploying to python, prompt if requirements.txt isn't found in the root
• Check a couple levels deeper for the app and provide a suggestion of which directory to deploy

[ejizba]

Not sure I'll be able to actually fix the issue in the current milestone, but I wanna try to add some telemetry around this scenario