Update Maven version, Maven plugins and dependencies

See merge request !23

- Update Maven to latest version (3.8.1).
- Update plugins to latest version (except for Jetty as we don't run latest version on our server).
- Set the version for Maven release plugin.
- Update dependencies to latest version (only patch version increase). Don't update Jetty (same motivation as above).

Update conf for OCSInventory and Rocket.Chat

See merge request !22

Adding the reference to get SonarQube data.

Use SPDX identifier and REUSE recommendation

See merge request !21

Attempt to solve #104 componentKey

See merge request !20

This reverts commit f3d1d36a.
This is done to add copyright and license information using SPDX and REUSE standards.

This reverts commit c419ec77.
This is done to add copyright and license information using SPDX and REUSE standards.

Add copyright license to source code

See merge request !19

Update conf for few projects

See merge request !18

# Conflicts:
#   data-collection/conf/ow2_projects.cfg.dist
#   data-collection/src/test/resources/ow2_projects.cfg

Update projects configuration to add Scancode URLs

See merge request !17