Delta now works in rails 4beta, ruby2, thinking-sphinx 3

removed FlagAsDeletedSet stuff.

updated gemspec… still failing ~30 tests (can only run thinking-sphinx
since I can't figure out how to get the latest version of flying-sphinx
in a gemspec file)

mostly regarding deleting
/usr/local/rvm/rubies/ruby-2.0.0-p0/bin/ruby -S rspec
./spec/flying_sphinx/resque_delta/delta_job_spec.rb
./spec/flying_sphinx/resque_delta/flag_as_deleted_job_spec.rb
./spec/flying_sphinx/resque_delta_spec.rb
./spec/thinking_sphinx/deltas/resque_delta/core_index_spec.rb
./spec/thinking_sphinx/deltas/resque_delta/delta_job_spec.rb
./spec/thinking_sphinx/deltas/resque_delta/flag_as_deleted_set_spec.rb
./spec/thinking_sphinx/deltas/resque_delta/index_utils_spec.rb
./spec/thinking_sphinx/deltas/resque_delta_spec.rb -c --format progress