Update switch_command.rb

Fix open alt-file by inserting a simple template,
bypassing code broken in TM2 and recent OS X.

The existing code locks up TM 2.0-alpha.9501 on Mavericks. 

There's an existing ticket from half a year or more ago, #38, but no commits. I've just had to re-discover the solution via Google.

There's missing functionality vs the original, e.g. not inserting model or controller templates depending on the file switched from, but is that worth having? File switching without crashing TM2 seems more important?