Fix „Run” command

Hi,

this should fix a bug in the „Run” command. `TextMate::Executor.run` expects all „words” in the shell command `xcrun --sdk macosx swift -i` to be a single element of an array. This commit reintroduces this behaviour, that seemed to got lost in the work done in commit b2a52fa1ff54ed9f91c86bad2affa47a80c9fa00.

Regards,
  René