Fix bug accessing sublime settings in thread

This fixes the RuntimeError caused by accessing sublime settings from outside the main thread:

```
Exception in thread Thread-37:
Traceback (most recent call last):
  File ".\threading.py", line 532, in __bootstrap_inner
  File ".\jshintify.py", line 150, in run
RuntimeError: Must call on main thread, consider using sublime.set_timeout(function, timeout)
```