Fix yaml-cpp issues (#36)

[isaachier]

Signed-off-by: Isaac Hier ihier@uber.com

[codecov]

Codecov Report

Merging #39 into master will increase coverage by 3.24%.
The diff coverage is n/a.

@@            Coverage Diff             @@
##           master      #39      +/-   ##
==========================================
+ Coverage   85.22%   88.46%   +3.24%     
==========================================
  Files          93       93              
  Lines        2240     2246       +6     
  Branches      206        0     -206     
==========================================
+ Hits         1909     1987      +78     
- Misses        253      259       +6     
+ Partials       78        0      -78

Impacted Files	Coverage Δ
src/jaegertracing/Config.h	95.23% <ø> (+4.76%)	⬆️
src/jaegertracing/baggage/RestrictionsConfig.h	100% <ø> (+8.33%)	⬆️
src/jaegertracing/propagation/HeadersConfig.h	100% <ø> (+4.16%)	⬆️
...egertracing/samplers/RemotelyControlledSampler.cpp	60.91% <0%> (-0.71%)	⬇️
src/jaegertracing/Span.h	93% <0%> (+1%)	⬆️
src/jaegertracing/SpanContext.h	98.27% <0%> (+3.44%)	⬆️
src/jaegertracing/samplers/Config.h	53.7% <0%> (+3.7%)	⬆️
src/jaegertracing/net/URI.h	100% <0%> (+4.54%)	⬆️
... and 17 more

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[black-adder]

What was the issue?

[isaachier]

I used a tool to optimize my #includes, but it totally undermined the case when certain libraries weren't installed, so had to fix here.