Adds rdkafka dependency, rdkafka client,
and notification for file close event

* commit 'd9862e8a':
  fix tests
  allow write to core

* commit '3cfaf09c': (29 commits)
  fix tests&build
  update mocks to a newer syntax
  update clang version
  more refactoring
  more refactoring
  refactor dispatcher errors
  fix tests
  fix test
  fix win tests
  fix tests
  refactor errors
  fix tests
  update error classes
  refactor erros
  fix linux build&tests
  refactor errors
  move getnext from examples
  refactor examples
  add folder structure to readme
  some more refactoring
  ...

* commit '607ae0f6':
  split cookbook examples into snippets

# Conflicts:
#	docs/site/examples/cpp/consume.cpp
#	docs/site/examples/cpp/consume_dataset.cpp
#	docs/site/examples/cpp/metadata.cpp
#	docs/site/examples/cpp/pipeline.cpp
#	docs/site/examples/cpp/produce.cpp
#	docs/site/examples/cpp/query.cpp