reduce request limit for resource intensive api calls

[alexskr]

/annotator and /recommender API calls are one of the most resource intensive calls. A single user hitting those API at the current limit of 15 request per second can create a significant strain on the backend. This change reduces request limit on those calls from 15 request per second per ip address to 1/5 of that.

[codecov-commenter]

Codecov Report

Merging #121 (92cd3f7) into develop (7c2ad53) will increase coverage by 0.03%. Report is 5 commits behind head on develop. The diff coverage is n/a.

@@             Coverage Diff             @@
##           develop     #121      +/-   ##
===========================================
+ Coverage    71.84%   71.88%   +0.03%     
===========================================
  Files           52       52              
  Lines         2845     2849       +4     
===========================================
+ Hits          2044     2048       +4     
  Misses         801      801              

Flag	Coverage Δ
unittests	71.88% <ø> (+0.03%)	:arrow_up:

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see 2 files with indirect coverage changes