fix send duplicate jvm data issue

fix testcase failed

Provide a new id generation and serialization mechanism

fix test case failed

Fix decode bug.

fix issue that httpclient plugin don’t work

* master:
  fix operation id of exit span incorrect issue

fix operation id of exit span incorrect issue

Add agentUUID in ApplicationInstance

Add agentUUID in ApplicationInstance

* 'master' of https://github.com/wu-sheng/sky-walking:
  fix miss transport entryServiceName and entryServiceId value
  fix miss entryServiceId and entryServiceName in ContextSnapshot  issue
  fix issue that open tracing activation set tag failed
  Make sure the JVM stop hook works #295
  Add jvm shutdown hook

# Conflicts:
#	apm-sniffer/apm-agent-core/src/main/java/org/skywalking/apm/agent/core/context/ContextSnapshot.java

fix miss transport entryServiceName and entryServiceId value

Add jvm shutdown hook

fix miss entryServiceId and entryServiceName in ContextSnapshot  issue

fix issue that open tracing activation set tag failed