chore: fix NumberFormatException when user uses comma in the catalog price

Finally fix #1513

Author: php-coder

src/main/java/ru/mystamps/web/support/spring/mvc/BigDecimalConverter.java

@@ -36,6 +36,10 @@ public BigDecimal convert(String source) {
 			return null;
 		}
 
+		return valueOf(source);
+	}
+	
+	public static BigDecimal valueOf(String source) {
 		String value = source;
 		if (source.indexOf(',') >= 0) {
 			// "10,5" => "10.5"

src/main/java/ru/mystamps/web/support/spring/mvc/PatchRequest.java

@@ -59,7 +59,7 @@ public Integer integerValue() {
 	}
 
 	public BigDecimal bigDecimalValue() {
-		return new BigDecimal(value);
+		return BigDecimalConverter.valueOf(value);
 	}
 
 }