This plugin would not be possible without @shoghicp 's FastTransfer plugin. All credit for the /server command goes to him.

A pocketmine plugin that allows proxying through the client

/server [player] <adress> <port>
Description: Transfer players to another server
Permission: knot.command.server
Default: OP

• Proxy Logging
• Set lobbys
• Hook up names to servers (/join )

This plugin comes with a built-in version of FastTransfer by @shoghicp called ChangeMyServer. Now, all this plugin does is redirect the client.