Revert "Use start-stop-daemon --chuid option to setuid to www-data."

This reverts commit a99ed038ecaf170574ee75cd5ddb12f252f9bc26.

On second thought, this will require a bit more care to ensure that all
of the paths radosgw needs to read/write from have the correct permissions
in the packages and so forth.

Signed-off-by: Sage Weil <sage@inktank.com>