Refactored code in schedule_menus method.

- Renamed schedule_menus method to report_selection_menus, and changed all it's callers.
- Moved report_selection_menus method to reports controller, as it is a common method schedules and widgets editor.
- Added spec tests for report_selection_menus method
- Changed message to be displayed for folders that do not have reports .

https://bugzilla.redhat.com/show_bug.cgi?id=1163952