Fix compiler errors in Xcode 7.
Fix compiler errors in Xcode 7.

Add a do-try-catch around compareSnapshotOfView.
Add repeated parameter names per Swift 2.0 language changes.

kevboh/Nimble-Snapshots,aterris/Nimble-Snapshots,aterris/Nimble-Snapshots,ashfurrow/Nimble-Snapshots,ashfurrow/Nimble-Snapshots,kevboh/Nimble-Snapshots