Use _.each

We need _.each for object iteration so might as well use it for arrays
as well
upgrade browserify/watchify
use native functions when possible
remove unused lodash functions
add style guide
Add section on how to download quill
Upgrade rich-text

Fixes #236
Format.prototype.removeConflicting removes all formats than cannot coexist

Line formats with 'exclusive: true' automatically remove all other
exclusive formats when applied.

The 'bullet' and 'list' formats are refactored to use 'exclusive: true'
Add support for h1, h2, h3