Merge pull request #543 from commercetools/Make_TypeSelector_public

Make TypeSelector constructor public, so it's easier to provide custom TypeSelectors

mongo/mongo-derivation/src/main/scala/io/sphere/mongo/generic/package.fmpp.scala

@@ -167,7 +167,7 @@ package object generic extends Logging {
   def mongoTypeSwitch[T: ClassTag, ${implTypeParams}](selectors: List[TypeSelector[_]]): MongoFormat[T] = mongoTypeSwitch[T, ${typeParams}](typeSelector[A${i}]() :: selectors)
   </#list>
 
-  final class TypeSelector[A: MongoFormat] private[mongo](val typeValue: String, val clazz: Class[_]) {
+  final class TypeSelector[A: MongoFormat](val typeValue: String, val clazz: Class[_]) {
     def read(any: Any): A = fromMongo[A](any)
     def write(a: Any): Any = toMongo[A](a.asInstanceOf[A])
   }