Modernize code with ES6-features and functional aesthetic

[georgemandis]

The code could stand to make better use of ES6 features and modern JavaScript coding styles. This might be the most wide-open issue in terms of solving and I'm open to all manners and discussion on the subject.

Some low hanging fruit and ideas to get started:

• Remove all instances of var
• Remove the custom event-listening code that existed for IE6(!!) compatibility
• Perhaps this could/should be rewritten as an ES6 Class?
• The one for loop could probably be rewritten to use forEach

If we can get a base rewrite that adheres to this we can break down the code and discuss more specific improvements.

[DavideCarvalho]

• Removing var is quite straightforward, this shouldn't be a problem (removed on #52)
• IE6 listeners is that "attachEvent" stuff?
• I don't see why not. The only problem is this iphone property, that has a bunch of code into it.

[georgemandis]

If you take a look at the 2.0 branch I've taken a pass at a complete rewrite. Will probably be easier to discuss specific changes from there.

Going to close this issue an an effort to consolidate things.