Bumped version to 1.1.0

[FinalAngel]

• Added support for Django 2.2 and django CMS 3.7
• Removed support for Django 2.0
• Extended test matrix
• Make sure placeholder operations are not shown in the admin
• Added isort and adapted imports
• Adapted code base to align with other supported addons
• Added translations

[codecov-io]

Codecov Report

Merging #31 into master will not change coverage. The diff coverage is n/a.

@@           Coverage Diff           @@
##           master      #31   +/-   ##
=======================================
  Coverage   32.86%   32.86%           
=======================================
  Files          16       16           
  Lines         712      712           
  Branches       71       71           
=======================================
  Hits          234      234           
  Misses        478      478

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