Silence SSG "generating" notices

[efc]

I generate a static site with over 6,000 pages and if I log the output from ssg:generate it ends up being a hefty long log. Plus, these "generating" messages use a cheap trick of outputting shell keystrokes to backspace over the line and print out the next line, which ends up pretty ugly in a log.

Is there any way to silence these "generating" messages? Note, I do like the summary information, so I would rather not just send the output to /dev/null.

If there is no way to handle this now, it would be great to be given a parameter or env variable or something that could tell SSG to be a bit less verbose.

Thanks!

[efc]

I created a pull request with one possible approach at #190