replace / with _ in beer names

Issue #29
We use the beer name as part of the file path for saving data... no problems there if we use MyBeer as a name,
the path is /path/to/MyBeer . However, if we use My/Beer as the name, the filepath becomes /path/to/My/Beer and
breaks everything. We simply replace / with _ to avoid this problem. Note- Windows has a TON of restricted chars
and COMBOS of chars that are restricted, but not addressed in this patch.