Don't assume that all errors are ConnectionErrors

[rohitpaulk]

Fixes an issue mentioned in #180.

The first part of the message ("Connection error") incorrectly led me to believe that the issue was in establishing a connection with Segment servers. This nudged my investigation towards HTTP-related issues and I eventually opened up a support ticket with Segment. We eventually realized the issue was a serialization error and were then able to correctly identify the problem and fix it. Had the error been labeled "Serialization error:" or something similar, finding the root of the bug would've taken much less time.

[f2prateek]

LGTM!

[codecov-io]

Codecov Report

Merging #187 into master will not change coverage.
The diff coverage is 100%.

@@           Coverage Diff           @@
##           master     #187   +/-   ##
=======================================
  Coverage   98.37%   98.37%           
=======================================
  Files          10       10           
  Lines         430      430           
=======================================
  Hits          423      423           
  Misses          7        7

Impacted Files	Coverage Δ
lib/segment/analytics/request.rb	100% <100%> (ø)	⬆️

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