add version/metadata actions to sandbox.sh

- metadata dumps out standard config options for the sandbox
  to make it clear where certain commands and config files are
  along with the location of the MySQL datadir
- this change extends MySQLVersion to handle version strings with
  comments and maintains a version tag as well - mostly useful
  for handling mysqld --version output, but should continue to
  handle plain '<major>.<minor>.<release>' strings as well
- Resolves issue #7