Miami startup LearnerNation was one of 21 companies worldwide selected Thursday to join the mentorship network Endeavor. LearnerNation, a cloud-based corporate training platform, will receive mentorship and access to capital, markets, and talent to grow its business. Co-founders Michael McCord and Michael Laas already count MasterCard, LG and Cartier as clients. RELATED CONTENT: 2014 People to Watch: Michael McCord "These past 7 months going through the selection process have been really valuable…