Updates that fall in line with latest changes

Retry policy now has an event that you can hook onto when it starts to
retry. Note this is only executed if it's determined that it needs to
retry.
Better reliability than using Environment.CurrentDirectory to get the
current working path.
Latest changes to the backup app exposed a number of events relating to
the compression part of the process. We hook into each one and ensure we
get ALL possible information when compressing something. I believe this
is only implemented for 7Zip at the moment.
Added a console log writer

Means all logs above and equal to information level are now output to
the console window too.