Refactor cookie methods for a simpler api

- Namespaced in the GOVUK namespace
- Follows jQuery style setter and getters
Remove tracking code which ins't used

It isn't used and really shouldn't be used.
Unify cookie functions and update welcome message

- Removed jQuery dependancy on welcome message.
- Only have one set of cookie functions
Remove hash-change nav javascript

- It isn't used by anything and doesn't belong in the template.
Remove button class fixing for IE

The current button implementation in the frontend toolkit doesn't use
these extra classes.
Fix syntax
Inlude libs then core, simplify welcome logic
Add newlines to the end of files
Merge pull request #12 from alphagov/js-refactor

JS Refactor