Release 0.6.0 "Coding Night 1"

Big release with lots of features being delivered and quite a few bugfixes as well. Lots of work is based on the community participation in our first "SonarQuest Coding Night" (yay!) and thus I decided to label the relase fittingly.
Due to some breaking changes, this release is not ⚠️ compatible with older versions of SQ.

Major features are (in no particular order):

• An admin may see and change role permissions #171 with thx @CINO-DE
• Dockerized with thx @sebastiansirch
• Table renaming for Oracle DB support
• #183 SonarQuest FE / Quests / Rework quests presentation layout (#187) with thx @hak6593
• #182 Quests now list their creator
• Angular 5 to 7 upgrade with thx @Sijoma ⚠️ this requires dev installations to be updated ⚠️
• #151 Admin UI shows the last login time of players with thx @ChristopherRBrown

Notable bugfixes:

• Various marketplace fixes (creating/editing/purchasing items, skill display)
• Dark/Light design switching
• Deletion of quests and adventures improved
• Avatar loading bug fixed
• missing levels in dev list in the admin ui
• #184 thx @fkoehne
• #185 thx @Sijoma
• #186 thx @ChristopherRBrown
• #161 thx @fkoehne
• Usability improvement: "New adventure" button disabled if it makes no sense to create an adventure with thx @Sijoma
• #181 thx @CINO-DE
• Minor refactorings with thx @nuhrberg

I am really proud of all the work and spirit the community has so far invested in SQ and I am looking forward to the future development of SonarQuest!

Chris