[WIP] Browser-based end to end testing with Robot

[kmader]

Getting end-to-end tests for the widget

Fixes #18

[codecov-io]

Codecov Report

Merging #19 into master will decrease coverage by 1.12%.
The diff coverage is n/a.

@@            Coverage Diff             @@
##           master      #19      +/-   ##
==========================================
- Coverage   89.18%   88.06%   -1.13%     
==========================================
  Files           4        4              
  Lines         148      176      +28     
==========================================
+ Hits          132      155      +23     
- Misses         16       21       +5

Impacted Files	Coverage Δ
cornerstone_widget/cs_widget.py	86.76% <0%> (-1.2%)	⬇️

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[bollwyvl]

For chrome in travis, in .travis.yml, i'd recommend

sudo: required
addons:
  chrome: stable

Once you get one browser working, you can trade build time for increasing the value of your work by testing with more browsers: for SCIENCE, I can now recommend Firefox ESR, which fully supports headless testing.

addons:
  firefox: latest-esr

I don't usually bother with edge or safari... ¯_ _/¯