Switch to camelCase instead of underscore_case

JavaScript is camelCase friendly.
Seems cool to use the same case style everywhere, particularly when
there is dom manipulation involved (eg: `document.querySelectorAll`,
`appendChild` etc…).
Merge branch 'camelCase' of github.com:MoOx/salvattore into MoOx-camelCase

Conflicts:
	dist/salvattore.js
	dist/salvattore.min.js
	src/salvattore.js
Merge branch 'MoOx-camelCase'
Add compatibility with underscore method names