Improve javascript & SCSS

[evangipson]

Javascript Improvements

• [x] Use jQuery ready instead of DOMContentLoaded, because of cross-browser support
• [x] Write a MICROSTOCKS.init function that does all the stuff that's currently in the anonymous function for DOMContentLoaded
• [x] After writing MICROSTOCKS.init, make a lot of the the public methods and variables private in the MICROSTOCKS modules

  SCSS Improvements

• [x] Take everything out of body - it doesn't need to be there! The space selector is expensive and we don't want unnecessary specificity!!!

[evangipson]

The javascript was taken care of in 9ebd084, and the SCSS was taken care of in https://github.com/evangipson/microstocks/commit/b2fa7d5b7046b65a259ca137ea6753aa28336f83.