If all test sample NT50 are less than lower limit, add prefix ">" to fold

[philiptzou]

The fold.js previously didn't handle potency ineffectiveness. All changes to this file is dedicated to this issue:

https://github.com/hivdb/chiro-frontend/commit/245947fc88d8072f7739615418185594c99ca7b7#diff-fcdd7dcccf6f830fc905ccd2dddc49b056d396002c6f22e93878a5dc5d49a919