Minor improvements on Address

* Update JSDocs
* Branch coverage 100%
* Removed duplicated test
* Updated names of tests
Some classes, `Address` and `PublicKey` at least, need refactoring, as their `validate` methods are using `new Something()` and catching an error: https://github.com/bitpay/bitcore/blob/master/lib/address.js#L374 https://github.com/bitpay/bitcore/blob/master/lib/publickey.js#L316

What do you think?