code in swift readme will not compile

I'm not sure if its due to Swift 1.2 however in step 12 the below code results in "Cannot assign to the result of this expression"
`rev["check"] = !wasChecked`
I believe `rev.properties["check"] = !wasChecked` is either what was meant to be, or now needs to be.

Also in step 13, when properties is declared it needs to be explicitly declared as a Dictionary or by default its created as NSDictionary and requires casting when passed into `doc.putProperties`