changed Request.headers from map to slice

[josephbergevin]

closes #10

[codecov]

Codecov Report

Merging #31 into master will increase coverage by 0.57%.
The diff coverage is 64.28%.

@@            Coverage Diff             @@
##           master      #31      +/-   ##
==========================================
+ Coverage   38.41%   38.98%   +0.57%     
==========================================
  Files           7        7              
  Lines         453      454       +1     
==========================================
+ Hits          174      177       +3     
+ Misses        251      250       -1     
+ Partials       28       27       -1

Impacted Files	Coverage Δ
request.go	15.89% <64.28%> (+1.46%)	⬆️

---

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 a27c151...49a1a53. Read the comment docs.