Special behavior on test builds

[ItsHarper]

On startup, the user should be notified that this is a test build. It will not receive updates, and it should be deleted as soon as they are done testing whatever was being tested. Tell them that if this is the only version they have, they should download the official version from GitHub (provide link)

The test build should have access to the dev tools.

The build should have all auto update functionality disabled.

The dist npm script should be replaced with one that checks for a CI environment.

[ItsHarper]

An idea for this:

package.js should temporarily change the version number to include "test". The program can then detect that and behave accordingly. We should be very careful that even if the script ultimately fails, the version number will be switched back.

Set name in the packaging options to include "test", and check for that. electron/packager#602 (comment)