server: Add the persisted models package

Includes the Block model which represents what is actually persisted.

server/app/com/xsn/explorer/models/persisted/Block.scala

@@ -0,0 +1,19 @@
+package com.xsn.explorer.models.persisted
+
+import com.xsn.explorer.models._
+
+case class Block(
+    hash: Blockhash,
+    previousBlockhash: Option[Blockhash],
+    nextBlockhash: Option[Blockhash],
+    tposContract: Option[TransactionId],
+    merkleRoot: Blockhash,
+    size: Size,
+    height: Height,
+    version: Int,
+    time: Long,
+    medianTime: Long,
+    nonce: Long,
+    bits: String,
+    chainwork: String,
+    difficulty: BigDecimal)

server/app/com/xsn/explorer/models/persisted/package.scala

@@ -0,0 +1,12 @@
+package com.xsn.explorer.models
+
+/**
+ * The package represents the models that are persisted in the explorer's database.
+ *
+ * One reason why we require different models than what is used on the RPC calls
+ * is that there are fields which shouldn't be persisted, for example, the number
+ * of confirmations for a block.
+ */
+package object persisted {
+
+}