Allow «validateCardExpiry()» to recieve plain card expiry input value

fix(formatCardNumber): correctly limits card length

This fixes #41.

Merge branch 'new-mastercard' of https://github.com/ahumphreys87/payment into ahumphreys87-new-mastercard

chore(build): build using webpack

BREAKING CHANGE: we now distribute the library in two different ways:

* the npm "main" is now `lib/index.js`, which is ES5 with require statements, compatible with webpack and browserify
* the `dist/payment.js` is a pre-built JS file that can be included in <script> tags

Fixes #33

* Updated regex for mastercard type to account for new series 2 range.
* Also added support for the '677189' versions of the card.

See: [this PR](https://github.com/thephpleague/omnipay-common/pull/88/) for further
details.

Changed the diners club format to: XXXX XXXXXX XXXX.

Fix mocha reporter option typo

fix(visa): add support for 19 digit visa card