Rename allow_guest_to_access_builds to public_builds

app/controllers/projects_controller.rb

app/models/ability.rb

app/views/projects/edit.html.haml

...0160202164642_add_allow_guest_to_access_builds_project.rb

db/schema.rb

doc/api/projects.md

features/steps/shared/project.rb

lib/api/entities.rb

lib/api/projects.rb

spec/features/builds_spec.rb

spec/features/commits_spec.rb

spec/features/security/project/public_access_spec.rb