Moved code to lightning

Updating codebase to make use of pytorch-lightning

• Main train/valid loops are handled by lightning
• Removed device-handling code
• Each model implements its own train/valid/predict steps
• Updated config files for use with lightning
• Using lightning checkpointing and logging callbacks
• Updated DeviceMonitor to be compatible with lightning

tests/data/lfs

-Subproject commit 69185f0d9ea67893722c5a840e2caa59946b3b83
+Subproject commit 9e3818d3fe0944697e91f171c59fdf035a22868c