Update exp_manager for Lightning 1.0
@okuchaiev that won't work sadly with multiple data loaders. Each will be tagged with a specific name prepended so exp manager cannot infer it. At least not unless we also attach a "default" validation wer to our logs 

We actually do attach a default "val_loss", with the default as the first dataloader passed to the validation filepath (can be changed with a flag). So we can add some logic to our wer logging to add a default wer to the logs too.  So can this: "modify ASR configs (for speech recognition models only) to monitor: "validation_wer" instead of "val_loss" by default" be done for a case of single data val loader at least (which is what our configs are)?
