Added support for Sublime Text 3

Hi Tim,

I've added support for Sublime Text 3 based on your Python 3 branch . I've tested the new version on my system with both ST2 and ST3 and it seems to work fine. When I change the settings they seem to get picked up properly and are applied as needed. To get the plugin to work under ST3 I needed to change a few things:

- Added an import to make Python 2.6 treat print as a function rather than an instruction
- Needed to change the import for *lesscompiler*. With a *Try...Exception* construction is the only way I got it to work, not sure if this is proper Python
- The settings are now read using the method *load_settings*. As far as I can tell this works well with the existing settings but I am not sure why you loaded the settings the way you did. Can you please verify that I haven't broken anything?

If you decide to merge my pull request I would like to suggest you add the plugin to [this](https://github.com/wbond/sublime_package_control/wiki/Sublime-Text-3-Compatible-Packages) list as a working plugin for ST3. It might give you some extra exposure.