Add a UI for editing Board of Directors

[belongstorachel]

As board members change, we would like to have a UI to manage changes when board members come onto the board, change titles, or if the board member wants to have their bio updated. We would also like to keep the history of who was a board member.

The UI should be protected and can be done with the Rails Basic Auth (http://api.rubyonrails.org/classes/ActionController/HttpAuthentication/Basic.html)
Similar to how it's now used in https://github.com/columbusrb/columbusrb.com/blob/master/app/controllers/speakers_controller.rb#L3