Add some TrustWorthy pragmas.

The following modules should be safe:

Control.Lens.Action
Control.Lens.Level
  - use Data.Profunctor.Unsafe (safely)

Control.Lens.Each
Control.Lens.Empty
  - use Data.Profunctor.Unsafe (safely)
  - dependencies with insufficient SafeHaskell support: vector, unordered-containers

Control.Lens.Internal.ByteString
  - implemented in terms of ByteString internals
Merge pull request #432 from int-e/safe-haskell

Add some TrustWorthy pragmas.