Implements Hunt basic create and get, and adds field validation to controllers

src/main/kotlin/net/halfbinary/scavengerhuntapi/model/domain/Hunt.kt

@@ -0,0 +1,13 @@
+package net.halfbinary.scavengerhuntapi.model.domain
+
+import net.halfbinary.scavengerhuntapi.model.HuntId
+import java.time.LocalDateTime
+import java.util.*
+
+data class Hunt(
+    val id: HuntId = UUID.randomUUID(),
+    val title: String,
+    val startDateTime: LocalDateTime,
+    val endDateTime: LocalDateTime,
+    val isTerminated: Boolean
+)