Multiple storage of APIs

Hello!

I needed to manage more than one API at time, and downloading and uploading files was a little repetitive. So I've added a new function in the header to allow  loading of different YAMLs storaged in the localstorage of the browser.

Now the YAML loaded in the Editor is saved as **yaml** (as it was before) and then specifically with the title of the api. So by doing this is possible to maintain several APIs at once!.

This can be tested on: http://www.gsole.cat/swagger-editor

Gerard

PS: petstore-api.herokuapp.com yaml I think that is failing in new versions, I think that I read about that.