make the log level configurable from roller config

currently, the log level applied to all components is `debug`

**task:**
add a new field in the `roller.toml` which would control the log level for all components, eg:

```
logging: debug # or info, etc.
```


or add a `logging` section where each component can be configured separately, eg:

```
logging:
  relayer: debug
  rollapp: info
``` 