Remove old mooc.fi logo, add new logo and new favicon

[Redande]

No description provided.

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 66.43%. Comparing base (871138e) to head (f1a15da).
Report is 1 commits behind head on master.

Additional details and impacted files

@@            Coverage Diff             @@
##           master    #1269      +/-   ##
==========================================
+ Coverage   58.87%   66.43%   +7.56%     
==========================================
  Files         141      144       +3     
  Lines        5843     6042     +199     
  Branches     1388     1434      +46     
==========================================
+ Hits         3440     4014     +574     
+ Misses       2199     1889     -310     
+ Partials      204      139      -65     

Flag	Coverage Δ
backend	66.43% <ø> (+7.56%)	⬆️

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