Ignore cors headers

[cbarraford]

the cache interferes with gin CORS, setting the headers twice (once by cache and once by cors), which is invalid.

Thanks to https://github.com/0987363/cache/commit/1882a7e344c628e49df703de9e34b1287c957613

[codecov-io]

Codecov Report

Merging #20 into master will decrease coverage by 5.51%. The diff coverage is 12.5%.

@@            Coverage Diff             @@
##           master      #20      +/-   ##
==========================================
- Coverage   71.79%   66.27%   -5.52%     
==========================================
  Files           1        1              
  Lines          78       86       +8     
==========================================
+ Hits           56       57       +1     
- Misses         20       27       +7     
  Partials        2        2

Impacted Files	Coverage Δ
cache.go	66.27% <12.5%> (-5.52%)	:arrow_down:

---

Continue to review full report at Codecov.

Legend - Click here to learn more Δ = absolute <relative> (impact), ø = not affected, ? = missing data Powered by Codecov. Last update 87f25cc...d1dc2ca. Read the comment docs.

[hashworks]

I think this can be closed with #38.