Log errors for messages that exceed the maximum size

[rohitpaulk]

#114

[codecov-io]

Codecov Report

Merging #143 into master will increase coverage by 0.11%.
The diff coverage is 100%.

@@            Coverage Diff            @@
##           master    #143      +/-   ##
=========================================
+ Coverage   98.38%   98.5%   +0.11%     
=========================================
  Files           9      11       +2     
  Lines         371     400      +29     
=========================================
+ Hits          365     394      +29     
  Misses          6       6

Impacted Files	Coverage Δ
lib/segment/analytics/message.rb	100% <100%> (ø)
lib/segment/analytics/worker.rb	100% <100%> (ø)	⬆️
lib/segment/analytics/defaults.rb	100% <100%> (ø)	⬆️
lib/segment/analytics/message_batch.rb	100% <100%> (ø)

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[rohitpaulk]

Tested this out in the console:

[rohitpaulk]

Note: This doesn't handle the case where a whole batch exceeds the allowed batch size:

The error logged out in that case is pretty ugly. This is an error the user shouldn't have to know about - as it could be entirely handled by the library. We could split one batch into multiple that each fall under the limited size. I'll handle this in a separate PR.

[rohitpaulk]

Ready for review.