* Extract LS context propagation into configurable propagator class
* Extract context prop test cases to LightStepPropagator spec
* Make LightStepPropagator easier to subclass
Constant lookup will search in Module.nesting before looking up
the inheritance chain, which makes constants hard to override
when subclassing. This commit prefixes constants in the
LightStep propagator with self.class in order to steer lookup
to the inheritance chain.
* Introduce B3 Propagator
This commit introduces a B3 Propagator where keys are properly
injected and extracted under the proper names. Special handling
of the trace id and sampled flag will come in subsequent commits.
* Propagate 16 byte trace ids for B3; use 16 byte ids internally
* Honor and propagate sampled flag for B3
* Clean up tests
* Specify default propagator for Tracer#configure
* Test against currently maintained Rubies
This updates our build matrix to test against Ruby versions that are
still under maintenance by the Ruby core team.
* The mutating tr! and downcase! methods are not chainable; don't chain them
* Make it easier to specify a propgator
* Update changelog for B3
Matthew Wear