Sanitize Input for Price Variables

- Updated the model to automatically format the price
- Updated the samples to reflect the new changes
- More Unit Tests

lib/PayPal/Common/FormatConverter.php

@@ -0,0 +1,34 @@
+<?php
+
+namespace PayPal\Common;
+
+class FormatConverter {
+
+    const TWO_DECIMAL_PLACES = '%0.2f';
+
+    /**
+     * Format the data based on the input formatter value
+     *
+     * @param $value
+     * @param $formatter
+     * @return string
+     */
+    public static function format($value, $formatter)
+    {
+        return sprintf($formatter, $value);
+    }
+
+    /**
+     * Format the input data to two decimal places
+     *
+     * @param $value
+     * @return string
+     */
+    public static function formatToTwoDecimalPlaces($value)
+    {
+        if (trim($value) != null) {
+            return static::format($value, self::TWO_DECIMAL_PLACES);
+        }
+        return null;
+    }
+}