Remove nondevise signups buttons and add signup fields to devise registration

- I removed the non-devise sign up options in the app on students and coaches index pages
- also I added all our original sign up fields to the devise registration page 
- added field headers on devise sign up page
- added field helptext on devise sign up and sign in pages
- put all fields in 2 coulmns


open to do:
- since I only removed the button for creating new persons (coaches and students), we need to remove the coaches and students new page in views and add in routes exceptions