Fix calling to getInputStream on errors

[yoavst]

When the status code is above 300 (Don't know for sure if for all codes, but for some of them for sure), getInputStream() throws FileNotFoundException and the stream is in getErrorStream().

[codecov-io]

Codecov Report

Merging #537 into master will increase coverage by 0.02%.
The diff coverage is 66.66%.

@@            Coverage Diff             @@
##           master     #537      +/-   ##
==========================================
+ Coverage   83.22%   83.24%   +0.02%     
==========================================
  Files          30       30              
  Lines        2438     2441       +3     
  Branches      277      277              
==========================================
+ Hits         2029     2032       +3     
  Misses        326      326              
  Partials       83       83

Impacted Files	Coverage Δ
...src/main/java/com/segment/analytics/Analytics.java	75.34% <0%> (ø)	⬆️
...ain/java/com/segment/analytics/internal/Utils.java	75.28% <100%> (+0.43%)	⬆️
...cs/src/main/java/com/segment/analytics/Client.java	91.66% <50%> (ø)	⬆️

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[f2prateek]

Is this documented anywhere?

[yoavst]

https://stackoverflow.com/questions/4633048/httpurlconnection-reading-response-content-on-403-error