Add status code for too many requests

[jahaynes]

No description provided.

[codecov-io]

Codecov Report

Merging #197 into master will increase coverage by 0.01%.
The diff coverage is 100%.

@@            Coverage Diff             @@
##             master   #197      +/-   ##
==========================================
+ Coverage     69.99%    70%   +0.01%     
- Complexity        0    679     +679     
==========================================
  Files           143    143              
  Lines          2953   2954       +1     
  Branches        239    171      -68     
==========================================
+ Hits           2067   2068       +1     
  Misses          840    840              
  Partials         46     46

Impacted Files	Coverage Δ	Complexity Δ
...o-api/src/main/java/com/spotify/apollo/Status.java	83.58% <100%> (+0.24%)	5 <0> (+5)	✅

---

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 81e3932...bb75b16. Read the comment docs.

[martina-if]

👍
@jahaynes This PR will add this to the new Apollo 2.0.0. If you would like to have it in the next minor release, please add the same PR against the branch 1.x