Update Ubuntu image to 20.04

[AndrewPiroli]

Ubuntu updated to the latest 20.04 LTS release

Ubuntu autoinstaller process updated to use the modern Ubuntu installer (subiquity) as debian-installer is no longer supported by Canonical. Scripts and packages no longer supported/used by Ubuntu 20.04 are removed. Packages and configuration updated to match current install documentation. Uses the dispatcher service instead of the cron job, but the cron job for Weathermap is still used.

OVA settings/defaults have not been changed, passwords for the DB, SSH, and WebUI have not been changed, features remain the same as previous builds: Etc/UTC Timezone 4 Poller Wrapper threads Syslog-ng Oxidized installed but not configured Weathermap plugin enabled Billing enabled RRDCached enabled Service checks enabled Syslog enabled

Here is an OVA generated by the build, obviously you should generate your own though: https://drive.google.com/file/d/1MqYgTMLHb8fiRO7fjQ5UalVHYwg11UzQ/view?usp=sharing

This should also close issues #20 #15 #14 and #6

I did not touch the CentOS side of things, so that is still very broken. I will probably look at that sometime... I am less motivated to put effort into the CentOS build because the current install docs call for CentOS 8, which is going EOL at the end of the year. I don't want to rewrite the CentOS build scripts now just to have to rewrite them for CentOS Stream (or whatever distro the project wants to support) in a few months.

[CLAassistant]

All committers have signed the CLA.

[murrant]

Looks great, thanks!