Add bootstrap css in project page

[codecov-io]

Codecov Report

Merging #354 into master will increase coverage by 0.01%. The diff coverage is n/a.

@@            Coverage Diff            @@
##           master    #354      +/-   ##
=========================================
+ Coverage   49.69%   49.7%   +0.01%     
=========================================
  Files         229     229              
  Lines       19821   19821              
  Branches     2891    2891              
=========================================
+ Hits         9851    9853       +2     
+ Misses       9564    9563       -1     
+ Partials      406     405       -1

Impacted Files	Coverage Δ
scanomatic/image_analysis/grid.py	75.93% <0%> (-0.76%)	:arrow_down:
scanomatic/data_processing/phases/segmentation.py	74.37% <0%> (+1.11%)	:arrow_up:

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[gdetrez]

I was wondering if it is preferred to have them here in the html or if it is better to have them in the js as import.

That's a good question. I think for the bootstrap file, since it is included in many pages, having it separated means that the browser can cache it.