Fix headers in messaging (#335)

* Fix headers in messaging

with this change the span related headers are changed to be compatible with messaging specs. The change is backwards compatible so we accept the old ones as input, and as output we're producing both new and old headers.

fixes #332

circle.yml

@@ -8,10 +8,11 @@ dependencies:
     - ./mvnw -s .settings.xml --fail-never dependency:go-offline || true
 test:
   override:
-    - ./mvnw -s .settings.xml clean install -nsu --batch-mode -Dmaven.test.redirectTestOutputToFile=true -Dorg.slf4j.simpleLogger.log.org.apache.maven.cli.transfer.Slf4jMavenTransferListener=warn
+    - ./mvnw -s .settings.xml clean org.jacoco:jacoco-maven-plugin:prepare-agent install -P sonar -nsu --batch-mode -Dmaven.test.redirectTestOutputToFile=true -Dorg.slf4j.simpleLogger.log.org.apache.maven.cli.transfer.Slf4jMavenTransferListener=warn
   post:
     - mkdir -p $CIRCLE_TEST_REPORTS/junit/
     - find . -type f -regex ".*/target/.*-reports/.*" -exec cp {} $CIRCLE_TEST_REPORTS/junit/ \;
+    - bash <(curl -s https://codecov.io/bash)
 
 notify:
   webhooks: