Add more functions on money

src/main/kotlin/com/cubetiqs/libra/moneyutils/Money.kt

@@ -1,7 +1,26 @@
 package com.cubetiqs.libra.moneyutils
 
-data class Money(
-    var value: Double,
-    var currency: String = "USD"
-)
+open class Money(
+    private var value: Double,
+    private var currency: String = "USD"
+) : StdMoney {
+    override fun getValue(): Double {
+        return this.value
+    }
 
+    fun setValue(value: Double) {
+        this.value = value
+    }
+
+    override fun getCurrency(): String {
+        return this.currency.toUpperCase()
+    }
+
+    fun setCurrency(currency: String) {
+        this.currency = currency
+    }
+
+    override fun toString(): String {
+        return "Money(value=${getValue()}, currency='${getCurrency()}')"
+    }
+}

src/main/kotlin/com/cubetiqs/libra/moneyutils/StdMoneyFormation.kt

@@ -0,0 +1,6 @@
+package com.cubetiqs.libra.moneyutils
+
+interface StdMoneyFormation {
+    fun format(): String
+    fun toMoneyString(overrideSymbol: Char? = null): String
+}