This gives the user enough notice to stay well updated, but won't spam
them if they're using resin-cli frequently.
Connects-to: #485
Change-type: patch
Signed-off-by: Cameron Diver <cameron@resin.io>
If `updateCheckInterval` has any meanginful value, the alert will be
shown one out of ten times, or something like that, making the user
likely to miss updates.
The underlying issue is that `update-notifier`, if it detects a cached
update notification, it deletes it, and only attempts to show it back if
`updateCheckInterval` is greater than `Date.now() - lastUpdateCheck`.
Current has the following problems:
- Our custom message gets printed even if the notifier doesn't contain
an update.
- The notifier box is deferred, therefore it's printed at the end of the
command. Since our custom message is printed at the beginning, it makes
no sense at all.
`update-notifier` persist its update check results in a file, which is
then read when running again the application.
If this file gets written when the application is being run as root, we
get ugly EPERM issues.
For this we use the `update-notifier` module with its default settings.
This module will print a nice banner prompting the user to run the
corresponding npm command to update.
