Fix CONTRIBUTEING.md pods link
Fix CONTRIBUTEING.md pods link

http://cball.me/organize-your-ember-app-with-pods/ is dead. https://www.programwitherik.com/ember-pods/ is a pretty good explanation.
HospitalRun/hospitalrun-frontend,HospitalRun/hospitalrun-frontend,HospitalRun/hospitalrun-frontend,HospitalRun/hospitalrun-frontend