[task] Improve README.md
[bugfix] Processing customer groups of gift rules

Fixes a typo, which prevents that gift rules for customer groups
beside 'NOT LOGGED IN' have no effect.

related #1
[task] Add modman file

related #4
[bugfix] Out of stock gifts

If your gift is out of stock, you are not able to fill your cart,
when the rule matches. So we need to just skip adding the gift.

related #2
[bugfix] Empty gift labels

Avoid adding messages if there is no gift label at all.

related #3
[task] Increment version number
[bugfix] Derivation of product conditions

Product conditions were derived wrongly from a class of the 
Mage_SalesRule module.

related #8
[bugfix] Product attribute conditions

Forces the loading the product attribute if this 
was not already done.

related #8
[bugfix] Multiple processing of gift rules

Prevents gift rules are applied repeatedly at run time.

related #8, #9
[bugfix] Success messages on adding gifts

Not in any case, when a gift is added to cart, success 
messages are displayed.

related #10
[bugfix] Compatibility with Magento CE 1.8

Provides compatibility with Magento CE 1.8. This changes are not
backward compatible with 1.7.
Merge branch 'development' of https://github.com/witrin/magento-gifts into development
Add composer.json