bug fixes for show/hide process buffer

+ Show Process Buffer will create a Lua process if one doesn't exist

+ Hide process buffer works correctly when buffer gets killed or is nil
  (delete-windows-on nil) could be executed before, which will do
  the wrong thing
Merge remote-tracking branch 'upstream/master'
fixed up tests && improved lua-kill-process
Merge remote-tracking branch 'upstream/master'
Merge pull request #69 from atomontage/master

Bug fixes for show/hide process buffer