Improve Logging

[jhamman]

Some of GARD's logging/error statements are hidden behind the debug option. I just ran into a case where GARD exited silently due to a configuration error (misaligned training/obs dates). These sorts of messages should be printed regardless of the debug option setting.

It would actually be nice to have a bit more control on the logging of GARD runs where we can print at the Error/Warning/Info/Debug levels.

[gutmann]

agreed