Remove unused methods.
Add vagrant option to cli

With this fix, you can access Vagrant VM easily like this.

```
$ itamae ssh --host=vagrant-vm-name --vagrant recipe.rb
```
Execute pre_action, set_current_attributes and show_differences
before running actions.
Bump up version
Fix a bug related with Logger.
Merge pull request #34 from mizzy/vagrant-option

Add vagrant option to cli
Change how to handle tempfile

Tempfile is removed when exit the block. So ocicasionally tempfile
is removed before send_file method.

So quit to use the block with tempfile and unlink file inside
ensure block.