Fixed image processing bugs

[ellbosch]

This PR fixes bugs pertaining to the camera view:

• Fixed image rotation issue, ensuring image is now in correct orientation before running inference
• Fixed issue where images were slightly distorted before getting processed
• Fixed issue where front-facing camera inverted view on x-axis
• Moved image processing task to background thread
• Changed screenshot to save the image used before inference rather than the screenshot of the entire view
• Stopped sending image processing for inference if no image found

Inference is now much more accurate—before we'd see incorrect results due to orientation and cropping issues, but these are now fixed with this PR.

Tagging #17