Issues/292 - add API Gateway

[jantman]

Adds API Gateway integration; fixes #292

[codecov-io]

Codecov Report

Merging #303 into master will not change coverage.
The diff coverage is 100%.

@@          Coverage Diff           @@
##           master   #303    +/-   ##
======================================
  Coverage     100%   100%            
======================================
  Files          24     25     +1     
  Lines        1789   1896   +107     
  Branches      276    293    +17     
======================================
+ Hits         1789   1896   +107

Impacted Files	Coverage Δ
awslimitchecker/utils.py	100% <100%> (ø)	⬆️
awslimitchecker/runner.py	100% <100%> (ø)	⬆️
awslimitchecker/services/vpc.py	100% <100%> (ø)	⬆️
awslimitchecker/services/apigateway.py	100% <100%> (ø)
awslimitchecker/version.py	100% <100%> (ø)	⬆️
awslimitchecker/checker.py	100% <100%> (ø)	⬆️
awslimitchecker/tests/services/__init__.py	100% <0%> (ø)	⬆️

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