Fixed project after AFNetworking module update.
[CRITICAL BUG] Fixed restoration bug caused by incorrectly check for unique identifier for vendor.

Every (re-)installation generates a new unique identifier for vendor.
Every purchase and restoration receipt will be tag with this new unique identifier.
But the latest receipt info might have a unique identifier for vendor from another device, from a previous installation, etc.
So we should only check if the purchase info matches receipt for device for receipt we restored with this device.
We should not check for unique identifier for vendor in latest receipt info.
This has caused a critical bug where restoration will always fails.

This commit attempts to fixed this issue.
Fix warning on CBDateFromDateString function
Merge pull request #24 from lxcid/bug/restoration-always-fails

[CRITICAL BUG] Fixed restoration bug caused by incorrectly check for unique identifier for vendor.
Merge pull request #25 from MaximKeegan/master

Fix Warning for CBDateFromDateString function
Merge pull request #20 from rsanchezsaez/master

Example project is broken after updating AFNetworking
Minor code re-formatting and copy-editing
Adding documentation

Re-arranging methods in implementation
Adding -productsWithRequest:success:failure:
Bumping version to 0.3.0
On systems < iOS 5, which do not support zeroing weak references, the
requestDidFinish delegate method will be called on the delegate after it
has already been releaed by the system. This works fine with zeroing weak
references, where a method call on nil will simply be ignored.
This poses a problem, however, if the reference in question has never been
zeroed out. The solution is to remove the in requestDidFinish on non
weak reference systems.
Merge pull request #26 from terhechte/master

Crash on non-zero-weak-reference systems