Code reorg prior to ST3 support

 * Separate quote/unquote code into functions outside the Commands
Sublime Text 3 support

 * Python 3 quote/unquote functions (py3 does not need any encoding/decoding, it expects unicode strings)
 * Detect ST2/ST3
 * Don't call sublime.load_settings() on import (it isn't available yet)
Merge pull request #4 from robcowie/feature/st3

Sublime Text 3 support