rename assignment to roster & added executor registry to roster

roster/src/test/java/ch/unisg/roster/RosterApplicationTests.java

@@ -0,0 +1,13 @@
+package ch.unisg.roster;
+
+import org.junit.jupiter.api.Test;
+import org.springframework.boot.test.context.SpringBootTest;
+
+@SpringBootTest
+class RosterApplicationTests {
+
+	@Test
+	void contextLoads() {
+	}
+
+}