whitespace cleanup
add --tag option to bundle_dbsake distutils command

- allow adjusting the version string in the generated binary
  so a git tag or other information can be included for
  troubleshooting purposes.
only pass defaults-file to mysqld_safe

- now all mysqld_safe options are included in the my.sandbox.cnf
  for easier maintainability.  All the necessary bootstrap
  options are written under [mysqld_safe] in my.sandbox.cnf and
  sandbox.sh only passes --defaults-file=/path/to/my.sandbox.cnf
  to mysqld_safe.  MY_SANDBOX_BASEDIR is set (per previous commit)
  so mysqld_safe can find appropriate commandline tools.
- To support looking up libexecdir, the discovered distribution
  instance is passed to the my.sandbox.cnf template.
update dbsake.sh action to deal with TAG=<value> options
remove sysconfig sourcing from sandbox.sh

- this is error prone and not well thought out and not
  used at all as far as I am aware. Removing for 2.0
lookup socket/pid-file from my.sandbox.cnf

- previously these were harcoded in sandbox.sh and changing
  these required updating both my.sandbox.cnf and sandbox.sh.
  Now my_print_defaults is used to lookup the option from
  the defaults file and no assumptions about their location
  are made by the sandbox script itself.