Fix publication api routes

[tusbar]

Fix 404 when published record doesn’t exist anymore.

Also get rid of publicationTarget and hardcode dgv for now.

[codecov]

Codecov Report

Merging #117 into master will increase coverage by 0.02%.
The diff coverage is 0%.

@@            Coverage Diff             @@
##           master     #117      +/-   ##
==========================================
+ Coverage   13.16%   13.19%   +0.02%     
==========================================
  Files          98       98              
  Lines        2211     2206       -5     
==========================================
  Hits          291      291              
+ Misses       1920     1915       -5

Impacted Files	Coverage Δ
lib/api/index.js	0% <0%> (ø)	⬆️
lib/api/routes/publications.js	0% <0%> (ø)	⬆️
lib/api/controllers/publications.js	0% <0%> (ø)	⬆️

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