Verwijder joda-time dependency en introduceer de modernizer plugin

[mprins]

en voer de door modernizer gevraagde aanpassingen door in de code

[codecov]

Codecov Report

Merging #1415 (f536042) into master (f536042) will not change coverage.
The diff coverage is n/a.

❗ Current head f536042 differs from pull request most recent head 7de8433. Consider uploading reports for the commit 7de8433 to get more accurate results

@@            Coverage Diff            @@
##             master    #1415   +/-   ##
=========================================
  Coverage     35.35%   35.35%           
  Complexity      809      809           
=========================================
  Files           411      411           
  Lines         19275    19275           
  Branches       1929     1929           
=========================================
  Hits           6815     6815           
  Misses        11851    11851           
  Partials        609      609           

---

Continue to review full report at Codecov.

Legend - Click here to learn more
Δ = absolute <relative> (impact), ø = not affected, ? = missing data
Powered by Codecov. Last update f536042...7de8433. Read the comment docs.