switch from ruby URI to Addressable::URI

When the source was a private github repos ruby 1.9's URI was borking with a not a URI error.

``` bash
lunix@madeira]  (master) -> be fpm-cook
DEBUG: url = git@github.com:foo/bar.git
/home/lunix/.rbenv/versions/1.9.3-p125/lib/ruby/1.9.1/uri/common.rb:176:in `split': bad URI(is not URI?): git@github.com:foo/bar.git (URI::InvalidURIError)
	from /home/lunix/.rbenv/versions/1.9.3-p125/lib/ruby/1.9.1/uri/common.rb:211:in `parse'
	from /home/lunix/.rbenv/versions/1.9.3-p125/lib/ruby/1.9.1/uri/common.rb:747:in `parse'
	from /home/lunix/.rbenv/versions/1.9.3-p125/lib/ruby/1.9.1/uri/common.rb:994:in `URI'
	from /home/lunix/.rbenv/versions/1.9.3-p125/lib/ruby/gems/1.9.1/gems/fpm-cookery-0.14.0/lib/fpm/cookery/source.rb:16:in `initialize'
	from /home/lunix/.rbenv/versions/1.9.3-p125/lib/ruby/gems/1.9.1/gems/fpm-cookery-0.14.0/lib/fpm/cookery/recipe.rb:84:in `new'
	from /home/lunix/.rbenv/versions/1.9.3-p125/lib/ruby/gems/1.9.1/gems/fpm-cookery-0.14.0/lib/fpm/cookery/recipe.rb:84:in `initialize'
	from /home/lunix/.rbenv/versions/1.9.3-p125/lib/ruby/gems/1.9.1/gems/fpm-cookery-0.14.0/lib/fpm/cookery/book.rb:16:in `new'
	from /home/lunix/.rbenv/versions/1.9.3-p125/lib/ruby/gems/1.9.1/gems/fpm-cookery-0.14.0/lib/fpm/cookery/book.rb:16:in `load_recipe'
	from /home/lunix/.rbenv/versions/1.9.3-p125/lib/ruby/gems/1.9.1/gems/fpm-cookery-0.14.0/lib/fpm/cookery/cli.rb:125:in `run'
	from /home/lunix/.rbenv/versions/1.9.3-p125/lib/ruby/gems/1.9.1/gems/fpm-cookery-0.14.0/bin/fpm-cook:7:in `<top (required)>'
	from /home/lunix/.rbenv/versions/1.9.3-p125/bin/fpm-cook:23:in `load'
	from /home/lunix/.rbenv/versions/1.9.3-p125/bin/fpm-cook:23:in `<main>'
```
[sporkmonger/addressable](https://github.com/sporkmonger/addressable) solves this issue.
I have not tested this extensively yet with other source types but hope to have some time later tonight.