added getAllCohorts and jsonSerialize to Cohort class
added getAllCohorts and jsonSerialize to Cohort class

 https://app.asana.com/0/202206849274532/206902611499173
 https://app.asana.com/0/202206849274532/206902611499174

deepdivedylan/aaaa-capstone,kdilts/aaaa-capstone,kdilts/aaaa-capstone,deepdivedylan/aaaa-capstone,kdilts/aaaa-capstone,deepdivedylan/aaaa-capstone,deepdivedylan/aaaa-capstone