PullAprove

[maggu2810]

openhab2-addons already uses PullApprove, so I don't it will harm to use it for openHAB Core, too.
It can be used to make the "Signed-off-by" requirements more visible.

I requested to add it:

A request to install PullApprove has been submitted on the @openhab account.

Who needs to have a look at?

[kaikreuzer]

I received the request and approved it.