initial commit to support GCE LB

add support targetPools, forwardingRules and httpHealthChecks API
add expectedTests and LiveTests for the above API
The endpoint param provides a function that returns a URI given a value. In the nova example, it returns the endpoint given the region. jclouds has a set of default functions to do that, that delegate to different region/zone suppliers. You can have a look at the [RegionToEndpoint](https://github.com/jclouds/jclouds/blob/master/core/src/main/java/org/jclouds/location/functions/RegionToEndpoint.java) function to see how it works and to the [keystone suppliers package](https://github.com/jclouds/jclouds/tree/master/apis/openstack-keystone/src/main/java/org/jclouds/openstack/keystone/v2_0/suppliers) to see how the suppliers where the function delegates are implemented in openstack.

This is needed, in general, when you need to perform an API call to get the endpoint (such as getting them from the keystone service catalog, or some complex work. In this case, if I'm not wrong, you can just move the `@Path` annotation to the "delegating" interface and all the methods in this one will already be scoped to that path.