Hiepluong dev request

Previous updates:
- Validation for empty name
- Drag drop for ordering (position)
- Separated Operation for Display student level and Achievement

additional updates:
- add id for li tags of nav bar, add span wrapper around the name of the sidebar item
- put ajax url into hidden field
- using function of javascript object data.success_func(result) and get rid of if else chunk
- using update_attributes(..) and get rid of case when statement