Delete inf-ruby-keys from ruby-mode-hook

See https://github.com/technomancy/emacs-starter-kit/pull/158

`inf-ruby-keys` is obsolete function.
New function is `inf-ruby-setup-keybindings`.
If this commit will cause to confuse on inf-ruby(irb on emacs),
see inf-ruby.el.
Change yas-snippets-dirs
Add snippets for rspec-mode
Move setting of dired to dired.el
Add dired-open-in-accordance-with-situation
Change dired-recursive-copies to always
Set dired-dwin-target to t