Restructured test dependencies

* All modules now have commons-test as test dependency.
* commons-test has dependencies to junit, hamcrest and mockito

main/core/pom.xml

@@ -73,6 +73,12 @@
 			<groupId>com.fasterxml.jackson.core</groupId>
 			<artifactId>jackson-databind</artifactId>
 		</dependency>
+		
+		<!-- Tests -->
+		<dependency>
+			<groupId>org.cryptomator</groupId>
+			<artifactId>commons-test</artifactId>
+		</dependency>
 	</dependencies>
 
 	<build>