fix dubbo rpc offline npe issue.

Merge branch 'refactoring-1.6.x' into master-1.6.x

* refactoring-1.6.x:
  update the tcc transaction dubbo, remove tccJavassist and tccJdk.
  update the TransactionContextEditor
  fix sample error.
  add CompensableTransactionFilter, remove TccJavassist.
  add dubbo filter

# Conflicts:
#	tcc-transaction-dubbo/src/main/java/org/mengyun/tcctransaction/dubbo/filter/CompensableTransactionFilter.java
#	tcc-transaction-dubbo/src/main/resources/META-INF/dubbo/org.apache.dubbo.rpc.Filter

update the version.