Robust logging

[scotthavens]

I'm trying to run snowav from the command line and there is a lack of logging when trying to process long time periods. If I try to do a whole run, it sits without any information printed out to the screen. It'd be great to align the standalone logger in snowav with those in SMRF and AWSM. For example, log the name of the package, put the logger above the parsing (which can take some time) so that a user can get direct feedback as soon as they run snowav.

[robertson-mark]

More robust logging added. This includes more debug logging statements for file loading, and moving the logger inside the processing function so the statements are more timely. The logger has to be initiated after parsing is complete, so that we can let snowav process an entire directory without knowing the start and end date (files can't be logged to until directory is created, and directory name includes start/end dates). However, now the log will at least show the files that have been loaded if there was an error.