[WIP] consistent spelling

- [x] stylesheet - Stylesheet
- [x] front-end - frontend - front end
- [ ] Full-Stack - Full stack
- [ ] Symfony2 Framework - form framework - Form framework
- [x] Save-handler - Save handler
- [ ] Dependeny Injection Tags - Dependeny Injection Container - dependeny injection container
- [ ] Event Dispatcher - event dispatcher
- [ ] Event Subscriber - event subscriber
- [x] Symfony2 Standard Distribution - Symfony2 Standard Edition
- [ ] Console Command - console command
- [x] email - Email - e-mail
- [x] Boolean - boolean 
- [x] web debug toolbar - Web Debug Toolbar
- [ ] Exception - exception
- [x] object-oriented - object oriented
At least, that's how Wikipedia uses it (I also think that this make sense since it's based on George Boole's name).