Clear role repository before seeding initial roles

Author: NourAlPha

src/main/java/com/podzilla/auth/seeder/DatabaseSeeder.java

@@ -17,6 +17,7 @@ public DatabaseSeeder(final RoleRepository roleRepository) {
 
     @Override
     public void run(final String... args) throws Exception {
+        roleRepository.deleteAll();
         roleRepository.save(new Role(ERole.ROLE_USER));
         roleRepository.save(new Role(ERole.ROLE_ADMIN));
         roleRepository.save(new Role(ERole.ROLE_COURIER));