Implemented climatic forecast for 30 days. Some refactoring.

src/test/java/com/github/prominence/openweathermap/api/utils/TestMappingUtils.java

@@ -0,0 +1,12 @@
+package com.github.prominence.openweathermap.api.utils;
+
+import java.time.Instant;
+import java.time.LocalDateTime;
+import java.util.TimeZone;
+
+public class TestMappingUtils {
+
+    public static LocalDateTime parseDateTime(int seconds) {
+        return LocalDateTime.ofInstant(Instant.ofEpochSecond(seconds), TimeZone.getDefault().toZoneId());
+    }
+}