* Use version to determine plugin protocol to use
* Remove field from ServeOpts
* Fix missing assignment, handle errors
* contraint -> constraint
* Inject the version string from the vault side
* Fix the version check
* Add grpc support check to database plugins
* Default to use grpc unless missing env var or fail on contraint check
* Add GRPCSupport test
* Add greater than test case
* Add go-version dep
* Start work on context aware backends
* Start work on moving the database plugins to gRPC in order to pass context
* Add context to builtin database plugins
* use byte slice instead of string
* Context all the things
* Move proto messages to the dbplugin package
* Add a grpc mechanism for running backend plugins
* Serve the GRPC plugin
* Add backwards compatibility to the database plugins
* Remove backend plugin changes
* Remove backend plugin changes
* Cleanup the transport implementations
* If grpc connection is in an unexpected state restart the plugin
* Fix tests
* Fix tests
* Remove context from the request object, replace it with context.TODO
* Add a test to verify netRPC plugins still work
* Remove unused mapstructure call
* Code review fixes
* Code review fixes
* Code review fixes
