subscription: support termination

This is a squash commit of pull request #25 with a few changes:

* fix imports
* fix failing test

Written-by: Omri Spector <omri.spector@gmail.com>
Signed-off-by: Pierre-Alexandre Meyer <pierre@mouraf.org>
Support deserialization of a pending subscription.

* <subscription> element may have a child <pending_subscription> element when subscription changes are scheduled at renewal.
Support Coupon Redemption API

Recurly API specification is described in
 http://docs.recurly.com/api/coupons/coupon-redemption

* RecurlyClient.redeemCoupon()
* RecurlyClient.getCouponRedemptionByAccount()
* RecurlyClient.getCouponRedemptionByInvoice()
* RecurlyClient.deleteCouponRedemption()

Also implemented coupon deactive API for unit testing.

* RecurlyClient.deleteCoupon()
Merge pull request #26 from oohira/support-pending-subscription

Support deserialization of a pending subscription.
Fix minor problems about Coupon Redemption API

* Change method signature of RecurlyClient.getCouponRedemptionByInvoice(String) to RecurlyClient.getCouponRedemptionByInvoice(Integer)
* Fix copy and paste mistake in Redemption.equals()
Merge pull request #27 from oohira/support-coupon-redemption

Support Coupon Redemption API
test: fix intermittent tests failures

Signed-off-by: Pierre-Alexandre Meyer <pierre@mouraf.org>
Fix a deserialization problem of RecurlyClient.getAddOns().
Merge pull request #28 from oohira/fix_get_add_ons_api

Fix a deserialization problem of RecurlyClient.getAddOns().
[maven-release-plugin] prepare release recurly-java-library-0.2.1
[maven-release-plugin] prepare for next development iteration
Added support for recurly.js signature generation
Removed common-codecs library in favor of Guava BaseEncoder
Doh, removed println
Merge pull request #29 from tonybaroneee/js-signature-gen

Added support for recurly.js signature generation
Fixed signature generation by adding toLowerCase
Added integration tests for recurly.js signature generation
Moved signature generation methods to static methods in new class, fixed tests
Deleted old tests and removed printlns
Updated README with new RecurlyJs class