Thomasv0.1

Hizo falta busqueda graciosa y 

Someone (or you) have updated the remote branch. That causes your remote branch become ahead of your current branch. (that is your local branch)

I suggest you to git pull --rebase origin master and push after that.

Github daba problemas de sincronización. No me dejaba bajar y tampoco subir, ni cambiar rama porque los cambios no se dejaron meter...