Add ExerciseRepository and ExerciseRepositoryImpl

application/module-exercise/src/main/java/org/fuseri/moduleexercise/exercise/ExerciseRepository.java

+package org.fuseri.moduleexercise.exercise;
+
+import org.fuseri.moduleexercise.common.DomainRepository;
+
+/**
+ * A repository interface for managing Exercise entities
+ */
+public interface ExerciseRepository extends DomainRepository<Exercise, String> {
+
+}
\ No newline at end of file

application/module-exercise/src/main/java/org/fuseri/moduleexercise/exercise/ExerciseRepositoryImpl.java

+package org.fuseri.moduleexercise.exercise;
+
+import org.fuseri.moduleexercise.common.DomainRepositoryImpl;
+import org.springframework.stereotype.Repository;
+
+/**
+ * An implementation of the ExerciseRepository interface
+ * Provides access to Exercise entities stored in a data source
+ */
+@Repository
+public class ExerciseRepositoryImpl extends DomainRepositoryImpl<Exercise, String> implements ExerciseRepository {
+}