Add simulator.getService method

[ganemone]

This provides a simple way of getting access to a service api registered on app.

[codecov[bot]]

Codecov Report

Merging #181 into master will decrease coverage by 1.2%. The diff coverage is 0%.

@@            Coverage Diff             @@
##           master     #181      +/-   ##
==========================================
- Coverage   89.04%   87.83%   -1.21%     
==========================================
  Files           3        3              
  Lines          73       74       +1     
  Branches       12       12              
==========================================
  Hits           65       65              
- Misses          6        7       +1     
  Partials        2        2

Impacted Files	Coverage Δ
src/index.js	70% <0%> (-2.42%)	:arrow_down:

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[AlexMSmithCA]

Thanks for adding this!

[ganemone]

!merge