[DAEMON-208] Enforce appcd version when loading plugins

We need a way to enforce that a plugin is compatible with specific appcd versions. We solve this by adding a appcdVersion to each plugin's package.json. When the plugin is detected, the plugin system will check that the plugin is compatible. This will lay the foundation for being able to inject appcd dependencies into plugins which solves issues of extraneous npm dependencies and instanceof not working if object is not the same.