Logging to file

Logging to console and browser-console is not so useful if the page is about to do a http redirect.

So I've added logging all those messages to the console, to make it easier to go back and trace what went wrong. Most of the changes in the file were to move `if(self::$settings->debug)` inside `_console` (so that it can log to file regardless of that flag.

Logfile path is set like:

    ::$settings->logfilePath = '/var/log/dwolla';

You might want to make it so that the logfile can only be enabled in sandbox mode, so that sensitive info doesn't end up sitting on harddrives somewhere - I wasn't sure.