Define plugin commands as instance of model classes
Fix typo:
expors =>
exports
Update plugin system based on new model systems
Update REST adaptor for the new plugin model
Export "model.isA" method as a utility
test: Update tests for plugin registerations
Fix missing "," between array elements
test: Define test  plugins as models
Load "model" correctly
test: Remove obsolete code (I forgot to remove it)
Rewrite socket.io adaptor around request-response and publish-subscribe model commands
Rename variables named "command" to "name" or "commandName" for readability
test: Update tests for new plugin spec
Remove codes to remove "publish" event listener because it is removed by socket.removeAllListeners()
Receive returned values from toBackend/toClient filters correctly
test: Build actually registered commands array correctly