Use endpoints for database seed and drop

...ri/modulecertificate/datainitializer/DataInitializer.java

...ertificate/datainitializer/DataInitializerController.java

application/module-certificate/src/main/resources/drop.sql

application/module-certificate/src/main/resources/import.sql

...useri/moduleexercise/datainitializer/DataInitializer.java

...leexercise/datainitializer/DataInitializerController.java

application/module-exercise/src/main/resources/drop.sql

application/module-exercise/src/main/resources/import.sql

...n/java/org/fuseri/modulelanguageschool/course/Course.java

...modulelanguageschool/datainitializer/DataInitializer.java

...uageschool/datainitializer/DataInitializerController.java

...java/org/fuseri/modulelanguageschool/lecture/Lecture.java

.../main/java/org/fuseri/modulelanguageschool/user/User.java

...cation/module-language-school/src/main/resources/drop.sql

...tion/module-language-school/src/main/resources/import.sql