Featured Content + Cloze Question Type + Transitions Refactoring

- Featured Content Backend
- Featured Content Front-end: a) Featured Content Model b) Landing View c) Storing of featured content statistics in local storage
-  Cloze Question Type
-  Refactoring of Transitions
-  Fixing statistics issues i.e. sendStatistics to server is working properly, the deletion of the local statistics table is handled by deleting all statistics for the courses of course list view  
- Layout polishing: added glow effect on the green ticks, improved some of the forms so that they all have a one border outline etc.