Get rid of jQuery in the admin part

[martinRenou]

We can use the trim modifier of Vue instead of the trim method of jQuery

[codecov-io]

Codecov Report

Merging #447 into master will not change coverage.
The diff coverage is n/a.

@@           Coverage Diff           @@
##           master     #447   +/-   ##
=======================================
  Coverage   95.33%   95.33%           
=======================================
  Files          88       88           
  Lines        4077     4077           
  Branches      259      259           
=======================================
  Hits         3887     3887           
  Misses        138      138           
  Partials       52       52

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