Analytics SDK fixes

[sandeep-paliwal]

Added openapi spec validation
Changed analytics SDK to return entire response
Unit test coverage to 100%
env file support for e2e tests

How Has This Been Tested?

unit tests

Types of changes

• Bug fix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds functionality)
• Breaking change (fix or feature that would cause existing functionality to change)

Checklist:

• I have signed the Adobe Open Source CLA.
• My code follows the code style of this project.
• My change requires a change to the documentation.
• I have updated the documentation accordingly.
• I have read the CONTRIBUTING document.
• I have added tests to cover my changes.
• All new and existing tests passed.

[codecov]

Codecov Report

Merging #36 into master will increase coverage by 5.95%.
The diff coverage is 100.00%.

@@             Coverage Diff             @@
##           master       #36      +/-   ##
===========================================
+ Coverage   94.04%   100.00%   +5.95%     
===========================================
  Files           3         3              
  Lines         168       168              
  Branches       15        15              
===========================================
+ Hits          158       168      +10     
+ Misses         10         0      -10     

Impacted Files	Coverage Δ
src/index.js	100.00% <100.00%> (+7.75%)	⬆️

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[shazron]

In general, we should not test specific output because the test server contents might change. Let's change it to test for success only like so: https://github.com/adobe/aio-lib-target/blob/master/e2e/e2e.js

[shazron]

Retracting e2e code comments, will file a separate issue.