Update run.js

- Fix the watch task in Windows 7 env.

Error log: 
```
RUN [?] App started
RUN {*} Change detected: layouts\.sublbb1.tmp

events.js:72 throw er; // Unhandled 'error' event
              ^

Error: ENOENT, stat 'C:\...\drywall\layouts\.sublbb1.tmp'
```