* Refactor plugin.proto and pluginbase.go to add support for metadata in connection context
* go fmt
* move test plugin out
* Refactor Dockerfile to build test plugin in e2e/testplugin directory
* mv testplugin -> testgrpcplugin
* add test for connection metadata
* enable logging to stdout
* Refactor Dockerfile to build test plugin in e2e/testplugin directory
* Add PipeCreateErrorCallback to handle pipe creation errors
* Add test for FailtobanPipeCreateFail
* Fix missing newline at end of file in pluginbase.go