Draft for libGDX Pay API.
Purchase object improved to accept both an integer or String in the constructor for the item identifier.
Merge branch 'master' of https://github.com/noblemaster/libgdx into iap
added gdx-pay to build
Merge branch 'master' of https://github.com/libgdx/libgdx
Merge branch 'iap' of https://github.com/libgdx/libgdx
Pay API:
 - removed PurchaseObserver - there is now only 1 single listener: PurchaseListener
 - itentifier changed to String (from int).
Merge branch 'iap' of https://github.com/libgdx/libgdx
Added payment processor stubs for Google Wallet/GWT and Stripe/Desktop.
Fix TextureUnpacker
GWT
Typo
Add support for DELETE and PUT

Closes #1985
add setCenterPosition and other methods to Actor
avoid raw Types when dealing with scene2d Cell

add generic types to more things in Table.java

fix error

fix error again because im bad
Merge pull request #2000 from jrenner/actor-centerpos

add setCenterPosition and other methods to Actor
Merge branch 'master' of https://github.com/libgdx/libgdx
Merge pull request #2002 from alex55i/unpackerfix

Fix TextureUnpacker
some scene2d ui docs
Merge pull request #2003 from jrenner/docs

some scene2d ui docs