Updated License

As per #254, this pull request updates the copyright date for this library up to 2014.
However this pull request also updates the copyright holders to be inclusive of all contributed works to the bitcoinjs-lib library throughout this period.

This should be acceptable as @justmoon's copyright notice would still be in effect for the work he originally contributed throughout 2011 and after; while recognizing new authors/contributors.

It also formats the LICENSE to be a bit more readable in its raw form.