[maven-release-plugin] copy for tag 0.31.0

v0.31.0 (opentracing#249)

Changes from v0.30:

* BaseSpan and ActiveSpan are simplified into a single Span class.

* Scope replaces ActiveSpan, removing the continuation concept. There is no longer a capture phase. Scopes are only activated and then closed.

* ScopeManager replaces ActiveSpanSource, and is expected to be passed to the tracer at initialization time.

* ScopeManager.activate(Span,bool) creates a Scope for the current context. The finishOnClose flag optionally calls Span.finish() on Scope.close().

* ScopeManager.active() returns the Scope associated with the current context.

* Tracer.activeSpan() returns the current value of Tracer.scopeManager().active().span() as a convenience.

* ThreadLocalScopeManager replaces ThreadLocalActiveSpanSource. It still uses thread-local storage for tracking active spans, but removes the reference counting used previously for span lifetime handling.

[maven-release-plugin] copy for tag 0.31.0-RC2

Mention the 0.30 compatibility package in the README. (opentracing#236)

* Mention the 0.30 compatibility package in the README.

[maven-release-plugin] copy for tag 0.30.0

Mock baggage (opentracing#129)

* Propagate mock baggage items

* Restore expanded imports

* Fix order of parameters in assertions

* Remove special case for no baggage

* Minor formatting to assist rebase

* Remove unnecessary imports

* Add prefix to baggage item keys

[maven-release-plugin] copy for tag 0.30.0.RC3

Change copyright comment in java files from /** */ style to /* */. (o…

…pentracing#143)

[maven-release-plugin] copy for tag 0.30.0.RC2

Adjust regexp escaping