Add optional Speak numbers as digits setting - #439

[AutoValueMutable] An @autovalue property that is a primitive array returns the original array, which can therefore be modified by the caller. If this is OK, you can suppress this warning with @SuppressWarnings("mutable"). Otherwise, you should replace the property with an immutable type, perhaps a simple wrapper around the original array.

[AutoValueMutable] An @autovalue property that is a primitive array returns the original array, which can therefore be modified by the caller. If this is OK, you can suppress this warning with @SuppressWarnings("mutable"). Otherwise, you should replace the property with an immutable type, perhaps a simple wrapper around the original array.