Re-add support for multiple Access-Control-Request-Headers field (fixes 

#184) (#186)

Normalize allowed request headers and store them in a sorted set (fixes 

#170) (#171)

Prevent empty Access-Control-Expose-Headers header (#160)

Fixes #159

Remove travis build report from README

Fix Access-Control-Request-Headers parsing issue for AWS API Gateway (#…

…141)

Add "Access-Control-Request-Private-Network" to Vary (#132)

Use go.mod replace in sub modules to point to same version

Fix example go.sum

public method to check cors domain (#115)

Add CORS headers to non-preflight OPTIONS too (#85)

Non preflight OPTIONS requests should work with CORS too.
This change is removing abort in actual request CORS handler for
OPTIONS request, so the client can receive the necessary headers
on such request.