Issue #1: Fix handling of default options

Hi,

i think i found the bug. The handling of default options is wrong. Because of the order the options are loaded rsync.rb overwrites all options that are already defined. Look at https://github.com/capistrano/capistrano/blob/master/lib/capistrano/setup.rb 

Whats by :rsync_options is always en empty array and the rsync command in :rsync will fail.

_Please note i am not a ruby developer and this is completely wrong._