Installing pgAdmin 4 in Runtime Mode (stand alone) in Linux

As it was not very clearly documented anywhere, we would like to share how
best to install PGadmin 4 on linux Mint and Ubuntu 16.04 in a virtual
environment as a stand alone desktop application (without the use of a
browser!).

PgAdmin 4 can be run in three ways:

- Server Mode in a web interface
- Local Mode in a web interface
- Local Mode in a standalone/runtime environment
The difference between the web interface and the runtime environment, is
that for the first you require to work from a browser. Whereas with the
runtime environments it runs as any other application on your desktop. This
is achieved by using Qt5, which creates a wrapper of the application. This
is a feature provided by the pgAdmin 4 team. However, on Ubuntu it wasn't
pre-build. Installing PgAdmin 4 for a runtime environment is a bit more
tricky than the other two, mostly because up until now it was not very well
documented. Especially it was unclear which dependencies it has on Ubuntu
and which options it needs at startup. After following this guide, you
will be able to run pgAdmin 4 in any of the three options on Ubuntu 16.04,
Linux Mint, or other Debian flavours.

Please find the installation guide here:
https://humandata.associates/blog/data-engineering/installing-pgadmin-4-runtime-mode

Hopefully someone can add the information to the pgadmin documentation and
even better turn this into one (or 3) debian packages...