Switch gender, ethnicity to free text fields.

Firstly: should have been on the ball with this to begin with. Many thanks to @megahbite to pointing this out, and @cczona for the wisdom of her RubyConf AU presentation (though given that was 2013, you'd think we would have been better at this to begin with).

Conflicts:
	app/models/person.rb
Merge pull request #15 from rubyaustralia/demographics

Switch gender, ethnicity to free text fields.