Updates for Ubuntu Server 18.0.4 LTS

[john-r2]

Hi Leon
The main changes to OpenFPC/docs/INSTALL.md are

1. Ubuntu 18 needs the Universe repository added to /etc/apt/sources.lit
2. there are some new dependencies
3. MySQL no longer lets you set a root password during installation, so there are steps included to enable a db root password
4. the db schema (originally from cxtracker, I'm guessing?) requires the node name to be an integer, so this is discussed.

Change to OpenFPC/etc/openfpc-default.conf to set NODENAME to 1 (integer to match schema)

Change to OpenFPC/openfpc-dbmaint to fix MySQL error that was causing the db user openfpc not to be created. Changed use 'mysql'; to use mysql

thanks
John

[john-r2]

Also, I added a doc on how to install the client manually. The deb package wasn't working for me.