backend support to add certificate number

[zhaofeng-shu33]

Related with Issue #31

[codecov]

Codecov Report

Merging #114 into master will increase coverage by 0.84%.
The diff coverage is 100.00%.

@@            Coverage Diff             @@
##           master     #114      +/-   ##
==========================================
+ Coverage   89.40%   90.24%   +0.84%     
==========================================
  Files           7        7              
  Lines         472      482      +10     
==========================================
+ Hits          422      435      +13     
+ Misses         50       47       -3     

Flag	Coverage Δ
#unittests	90.24% <100.00%> (+0.84%)	⬆️

Impacted Files	Coverage Δ
app.py	84.40% <100.00%> (+0.29%)	⬆️
test.py	100.00% <100.00%> (ø)
jobs.py	94.00% <0.00%> (+6.00%)	⬆️

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