Refactors form into a partial, renders it in new/edit
Renders youtube link as a link
Adds link to exercise list in the navigation
Adds exercises/index content
Adds a back button to go back to indexes
Adds PersonalRecord model and migrations
Changes PersonalRecord's record column to pr, due name conflict
Adds specs for personal record validations
Adds personal records controller and spec
Adds belongs to user and exercise in personal_record
 Adds routes for personal_records
Adds spec and controller actions for personal_records_controller