AE staging for github data initialization

I made two changes that are going to be inconsequential soon.  But I didn't want to just commit them to the data-initialization branch because I didn't want to interfere with files you might be working with (without talking to you about it first).

1) The config/initialization/open_food_network.rb  file still had the  ".example"  extension on the end, so I removed it (this is equivalent to deleting that file)
2) in seeds.rb, I changed how the path to the suburbs_seeds.rb file is created.  When I run this with my debugger (RubyMine), the <code>require_relative</code> doesn't work. So I changed it to a File.expand(...,__FILE__) call.   Soon this line will be changed anyway (or deleted altogether).

If you want to hold off on doing this pull request, that's fine.  I thought I'd get these little changes up here (1) so I wouldn't forget that I have them on my local machine (working branch), and (2) so I could practice creating a pull request here.