drug matrix object

[mariekers]

Convert drugs used into it's own django object so PPP can modify the list in the django backend

[mariekers]

Users should be able to select multiple items from the drugs used dropdown

[mariekers]

Create table to allow PPP to check off drugs used (and would allow them to add more drugs to matrix via admin site)

participant_id | heroin | crack/cocaine | k-2 | methamphetamines | fentanyl | opioids | other
12345A | 1 | 0 | 0 | 1 | 0 | 0 | marijuana