Rewritten to allow user configuration and switching theme alongside color scheme

I find this incredibly useful, and rewrote it to incorporate the following:

1. Configuration in a .sublime-settings file to easily select other, non-Solarized color schemes
2. Allow to also change the theme to match the color scheme (defaults to Soda Light/Dark)
3. Don't touch global sublime.settings, instead write current state to plugin settings and dynamically update views as they are shown

I made this last change primarily because I prefer not to have a plugin write to my global settings, but also because a Markdown plugin I use overrides the global color scheme and SolarizedToggle therefore didn't work for Markdown files. Dynamically updating the view solves this problem.

Obviously these are pretty fundamental changes so not sure if you want to incorporate!