A farmer personality is one who prefers security. Who is accustomed to following the rules and is risk averse. He or she prefers to cultivate, than to hunt. Hence the term farmer personality.
A hunter personality is some one who loves freedom. A go getter. Someone who loves the 'hunt'.
Note: Do not take the terms "farmer" or "hunter" literally. Its not the profession, but a generalisation of mentality/personality. I did not originate these terms, but take resposibility of reproducing it here.