Allow to manage sauce tunnel

[archlichking]

This PR allows

1. launch up sauce tunnel for each test run and close it eventually after the run
2. use existing sauce tunnel for every test
3. validate tunnel config

[codecov-io]

Codecov Report

Merging #4 into master will increase coverage by 5.03%.
The diff coverage is n/a.

@@            Coverage Diff             @@
##           master       #4      +/-   ##
==========================================
+ Coverage   84.73%   89.76%   +5.03%     
==========================================
  Files           5        6       +1     
  Lines         249      391     +142     
  Branches       46       77      +31     
==========================================
+ Hits          211      351     +140     
- Misses         38       40       +2

Impacted Files	Coverage Δ
lib/settings.js	100% <0%> (ø)	⬆️
lib/tunnel.js	97.46% <0%> (ø)
lib/profile.js	90.66% <0%> (+0.25%)	⬆️
lib/configuration.js	98.64% <0%> (+0.57%)	⬆️
lib/executor.js	71.26% <0%> (+18.43%)	⬆️

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