- fixes frontend nr. 112 - code template file visibility

src/ClientServer/Config/Constants.cs

...Server/Controllers/Core/AssessmentStatisticsController.cs

...xerciseAfterSolution/DoExerciseAfterSolutionController.cs

...Server/Controllers/Core/Exercises/DoExerciseController.cs

...er/Controllers/Core/Exercises/ExerciseEditorController.cs

...Server/Controllers/Core/Exercises/SubmissionController.cs

...lientServer/Controllers/Core/Testing/TestingController.cs

src/ClientServer/Helpers/UserSolutionHelper.cs

...Migrations/20190501142551_HiddenTemplateFiles.Designer.cs

...ntServer/Migrations/20190501142551_HiddenTemplateFiles.cs

...tions/20190501143221_RenameTemplateVisibility.Designer.cs

...ver/Migrations/20190501143221_RenameTemplateVisibility.cs

src/ClientServer/Migrations/SyndromDbContextModelSnapshot.cs

src/ClientServer/Models/Exercises/TemplateFile.cs

src/ClientServer/Schedulers/SubmissionAssessmentScheduler.cs