Add access modifiers and init

[maveric94]

Adds access modifier of mock class to all its members.

public protocol Foo {
   func bar()
}

public class FooSpy: Foo {
    public var invokedBar = false
    public var invokedBarCount = 0

    public init() {
         fatalError("Not implemented")
    }

    public func bar() {
        invokedBar = true
        invokedBarCount += 1
    }
}

It's useful when mocks are in separate module and saves you from adding modifiers manually. Also adds dummy init when mock is public or open and no init was generated.

[willinDrive]

Yes, I want this feature too. =)