update Subscription object to current Stripe API (added quantity field)

Signed-off-by: Markus Jura <markus.jura@googlemail.com>
version 1.1.4: Update case classes Coupon, Discount, Subscription to current Stripe API json objects (Stripe API version: 2013-02-13)

Changelog:
== 1.1.4 2013-08-13
* Update case classes to current Stripe API json objects (Stripe API version: 2013-02-13)
* Updated case classes: Coupon, Discount, Subscription

Signed-off-by: Markus Jura <markus.jura@googlemail.com>
add .DS_Store files to .gitignore

Signed-off-by: Markus Jura <markus.jura@googlemail.com>
version 1.1.4: Fix unit tests

Signed-off-by: Markus Jura <markus.jura@googlemail.com>