Add CoreDefinition scala class

* Scala model for core definitions
* support for reading and writing Json format

CoreDefinition.scala

+import scala.io.Source
+import play.api.libs.json._
+import play.api.libs.functional.syntax._
+
+/**
+ * Basic definition of a core for IP-XACT packaging.
+ **/
+case class CoreDefinition(name: String, vendor: String, library: String, version: String, root: String) {
+  import CoreDefinition._
+  def write(filename: String) : Boolean = try {
+    val fw = new java.io.FileWriter(filename)
+    fw.append(Json.toJson(this).toString)
+    fw.flush()
+    fw.close()
+    true
+  } catch { case ex: Exception => println("ERROR: " + ex); false }
+}
+
+/**
+ * Contains methods for reading a core definition from Json.
+ **/
+object CoreDefinition {
+  implicit val coreDefinitionWrites : Writes[CoreDefinition] = (
+      (JsPath \ "name").write[String] ~
+      (JsPath \ "vendor").write[String] ~
+      (JsPath \ "library").write[String] ~
+      (JsPath \ "version").write[String] ~
+      (JsPath \ "root").write[String]
+    )(unlift(CoreDefinition.unapply))
+
+  implicit val coreDefinitionReads : Reads[CoreDefinition] = (
+      (JsPath \ "name").read[String] ~
+      (JsPath \ "vendor").read[String] ~
+      (JsPath \ "library").read[String] ~
+      (JsPath \ "version").read[String] ~
+      (JsPath \ "root").read[String]
+    )(CoreDefinition.apply _)
+
+  def read(filename: String) : Option[CoreDefinition] = try {
+    val contents = Source.fromFile(filename).getLines.mkString("\n")
+    val json = Json.parse(contents)
+    json.validate[CoreDefinition] match {
+      case s: JsSuccess[CoreDefinition] => Some(s.get)
+      case e: JsError => { println("ERROR: " + e); None }
+    }
+  } catch { case ex: Exception => println("ERROR: " + ex); None }
+}