Updated API to handle more responses and errors

[local-minimum]

1. Handle Internal server error and similar that causes errors that are not formatted as JSON.
2. Handle 200 responses with the old success: false pattern.

[codecov-io]

Codecov Report

Merging #415 into master will increase coverage by 0.04%. The diff coverage is 90.9%.

@@            Coverage Diff             @@
##           master     #415      +/-   ##
==========================================
+ Coverage   41.63%   41.67%   +0.04%     
==========================================
  Files         216      216              
  Lines       17127    17134       +7     
  Branches     2954     2954              
==========================================
+ Hits         7130     7141      +11     
+ Misses       9580     9559      -21     
- Partials      417      434      +17

Impacted Files	Coverage Δ
scanomatic/ui_server_data/js/src/api/API.js	93.33% <90.9%> (-6.67%)	:arrow_down:
scanomatic/data_processing/phenotyper.py	27.51% <0%> (ø)	:arrow_up:
scanomatic/data_processing/phases/features.py	17.23% <0%> (ø)	:arrow_up:
scanomatic/ui_server/tools_api.py	8.77% <0%> (ø)	:arrow_up:
scanomatic/ui_server/general.py	23.48% <0%> (ø)	:arrow_up:
scanomatic/qc/phenotype_results.py	0% <0%> (ø)	:arrow_up:
scanomatic/io/source.py	18.08% <0%> (ø)	:arrow_up:
scanomatic/ui_server/data_api.py	9.65% <0%> (ø)	:arrow_up:
scanomatic/image_analysis/grid.py	76.69% <0%> (+0.75%)	:arrow_up:
scanomatic/data_processing/phases/segmentation.py	74.65% <0%> (+0.83%)	:arrow_up:

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