subject model added; survey create form removed for student
nav menu added to surveys page
subjects controller added; surveys resource nested into subjects
subjects are added to seeds; surveys by subject query implemented
subject nav menu added as separate partial
subject menu active li highlight
survey_run controller added
survey_run#run action implemented
survey nested form added on survey_run page
result calculating is implemented
ERD(Entity-Relationship Diagrams) visualizer added
survey_result entity added
survey result now will be saved to db
survey_run#view_results action implemented; survey_results added to seeds