#11 Adds basic trade persistence

- Includes a MongoDB entity, and its corresponding repository

src/main/kotlin/com/preslavrachev/cryptotrader/mvc/model/TradeRecord.kt

@@ -0,0 +1,13 @@
+package com.preslavrachev.cryptotrader.mvc.model
+
+import org.springframework.data.annotation.Id
+import java.time.LocalDateTime
+
+data class TradeRecord(
+        @Id var id: String? = null,
+        val amount: Float, /* always in relation to the quote currency */
+        val quoteCurrency: String, /* e.g. BTC in BTC/USDT */
+        val baseCurrency: String, /* e.g. USDT in BTC/USDT */
+        val executionDateTime: LocalDateTime = LocalDateTime.now(),
+        val orderScope: OrderScopeEnum = OrderScopeEnum.DEMO
+)

src/main/kotlin/com/preslavrachev/cryptotrader/persistence/repository/TradeRecordRepository.kt

@@ -0,0 +1,6 @@
+package com.preslavrachev.cryptotrader.persistence.repository
+
+import com.preslavrachev.cryptotrader.mvc.model.TradeRecord
+import org.springframework.data.mongodb.repository.MongoRepository
+
+interface TradeRecordRepository: MongoRepository<TradeRecord, String>