Unifi OS removed keytool in v3.1+ and other updates to unifi deploy hook

[3VAbdAVE]

Ubiquiti removed keytool from UnifiOS ~v3.1, but still uses a JKS keystore with a self-signed for the console application. This script probably shouldn't be auto-installing packages on appliances, but this now explains what's up to the user and lets them decide when it fails on a missing keytool.

The Unifi console is not configured to use strong cipher suites required by default letsencrypt RSA certificates, so update the configuration prior to service restart.

In my initial attempts to use this deploy hook, it broke and I had to hunt down original certificates, so backup the existing certificates, which we just assume are working.

[Neilpang]

fix the format errors.

[medmunds]

Ref #3359