rename files

- HlaejaServiceApplication to Application
- rename application.properties to application.yml

src/test/kotlin/ltd/hlaeja/ApplicationTests.kt

@@ -4,7 +4,7 @@ import org.junit.jupiter.api.Test
 import org.springframework.boot.test.context.SpringBootTest
 
 @SpringBootTest
-class HlaejaServiceApplicationTests {
+class ApplicationTests {
 
     @Test
     fun contextLoads() {