- added migration to remove assets from db because they are now in the file system

src/ClientServer/Config/Constants.cs

...ollers/Core/CustomProjects/EditCustomProjectController.cs

...xerciseAfterSolution/DoExerciseAfterSolutionController.cs

.../Controllers/Core/Exercises/ExerciseOverviewController.cs

...ntrollers/Core/Exercises/TutorViewAssessmentController.cs

src/ClientServer/Db/YapexDbContext.cs

...r/Migrations/20190728133647_RemoveOldDbAssets.Designer.cs

...ientServer/Migrations/20190728133647_RemoveOldDbAssets.cs

src/ClientServer/Migrations/SyndromDbContextModelSnapshot.cs

...tServer/Models/CustomProjects/CustomProjectDescription.cs

src/ClientServer/Models/CustomProjects/CustomProjectTest.cs

src/ClientServer/Models/Exercises/Asset.cs

src/ClientServer/Models/Exercises/ExerciseDescription.cs

src/ClientServer/Models/Exercises/Tests/CustomTest.cs

src/ClientServer/Models/Exercises/Tests/CustomTestAsset.cs

src/ClientServer/Models/Exercises/Tests/Test.cs

src/ClientServer/Models/Exercises/Tests/TestAsset.cs

src/ClientServer/Models/Interfaces/IDescription.cs

src/ClientServer/Workers/SubmissionAssessmentWorker.cs