Revised file processing screens on the backside of miniLock

Here is an implementation of the human interface design mentioned in issue #42.

And 3 videos that show it off:

Alice encrypts passport to Bob
https://vimeo.com/101773171

Save a secret song for my parents
https://vimeo.com/101773412

Crazy Town
https://vimeo.com/101773420
Sorry.

The reason why this is bad is because it relies on a ton of moving parts, unreliably, in order to determine a vital status regarding current encryption/decryption. This should be determined internally and ui.js should *only* be responsible with showing the results, not parsing strings that could be changed at any moment and that aren't there to inform the backend.

Notice that the crypto.js worker is already designed to be passing a postMessage on error, with the following parameters:
```	
postMessage({
	operation: 'decrypt',
	error: true
})
```

Those parameters are exactly there to provide a reliable response used to gauge what's happening in the software.