added dispose-method -> TODO: testing (+3 squashed commit)

Squashed commit:

[8cada2a] alternate implementation works now (alpha)

[23dd017] added some methods for amazon IAP

[a95e930] integrated amazon sdk.jar and empty amazon IAP manager (+1 squashed commits)

Squashed commits:

[a95e930] integrated amazon sdk.jar and empty amazon IAP manager
moved amazon IAP manager to its own package: gdx-pay-android-amazon
Merge pull request #18 from just4phil/amazonMgr

alternate amazon IAP purchase manager