Interactive visualization of Ai2-THOR scenes when running on remote machine (X11 forwarding)

I've setup my instance for X11 forwarding and utiltites like xeyes and glxgears work just fine. However, when I try to instantiate an AI2Thor controller, for example by executing this: `controller = Controller(scene="FloorPlan10")`, a white screen pops up and disappear. However, the Unity player doesn't pop up at all. I executed this too: `/home/ubuntu/.ai2thor/releases/thor-Linux64-2cca88de394ff1fa3f85f9ee3585444552059da9/hor-Linux64-2cca88de394ff1fa3f85f9ee3585444552059da9` that resulted in the same result (Unity not coming up).

I would like to point out that this works perfectly when I don't have X11 Forwarding enabled (through `-X` to `-Y`). In fact, the sample script (shared underneath), captures an image from an AI2Thor scene. I am able to FTP it to my local machine and view it.

```
from argparse import ArgumentParser
from ai2thor.controller import Controller
from PIL import Image

def main(size):
controller = Controller(scene='FloorPlan3_physics',
gridSize=0.25, snapToGrid=True,
width=size, height=size,
agentCount=1,
)

event = controller.step(action='MoveAhead')
img = Image.fromarray(controller.last_event.frame)
img.save('temp_' + str(size) + '.png')

if __name__ == '__main__':
arg_parser = ArgumentParser()
arg_parser.add_argument('--size', type=int, default=300)
args = arg_parser.parse_args()
main(args.size)
```

I am using a conda environment having Python 3.8.0. The AI2Thor version I am using is encapsulated in this repo: https://github.com/alexa/teach and I have this result:
`import ai2thor as ai`
`ai.__version__`
`'3.1.0'`

The output from glxinfo | grep version

`debug1: client_input_channel_open: ctype x11 rchan 3 win 65536 max 16384`
`debug1: client_request_x11: request from 127.0.0.1 38584`
`debug1: x11_connect_display: $DISPLAY is launchd`
`debug1: channel 1: new [x11]`
`debug1: confirm x11`
`server glx version string: 1.4`
`client glx version string: 1.4`
`GLX version: 1.4`
`OpenGL version string: 1.4 (2.1 Metal - 76.3)`
`debug1: channel 1: FORCE input drain`

`glxgears` and `xeyes` are running smoothly but I am not able to work with AI2Thor here. Can you please help here? @ekolve