GitLab

Avoid displaying wget output when checking wget version by redirecting the
output to /dev/null (per review).

If the wget version is lower than 1.19, the retry-on-http-error is not
included.

Combined ng_test into a single task with using debug flag.

Runs Chrome with --no-sandbox as it is required in CI when running as root.

In addition, ci_ui runs ng_test task.

[#412] moved back to 1.7.3 version, added print while checking help, reduced Rakefile ui system test function

Unset DESTDIR while doing npm install because it uses DESTDIR for something
else, leaving some garbage in the install directory.

[#366] added run to --db-trace-queries in Rakefile while running server for development and when dbtrace is true

It also requires a hack to make publishing an image working.

- added many checks for missing arguments
- moved session manager to NewRestAPI where all resources are allocated
  and to make it available in the tests

 - this affected build on docker on ubuntu 20.04

Use the guidelines from the Prometheus documentation about writing
exporters*. Implement a Collector for the exporter and create
new metrics each time with MustNewConstMetric in the Collect()
call.

Add a couple of simple metrics (boot time, config time, current time,
and incoming queries).

* https://prometheus.io/docs/instrumenting/writing_exporters/

- added EventCenter for receiving events from other modules
  and dispatching them to subscribers using server-sent events
- added events panel in UI, in dashboard page
- added entity links component in UI for presenting in UI entities
  link machine or app as an exposed box with link
- in Rakefile task serve_ui is changed: now it only builds UI,
  and UI is served by stork server over 8080 port and not using
  angular cli server by 4200 port (this is caused by not working
  SSE in angular cli proxy)
- added submitting events in several places

Now all is built in single contaier and then demo containers
are pulling in artifacts built in this single container.