[OSJC-101] Add support for setting and retrieving additional gear storag...

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I added a IDeployedStandaloneCartridge#getAdditionalGearStorage and delegated to ApplicationResource behind the scenes. Since ApplicationResource currently wont cache the gear groups (TODO comment exists) we wont get hurt, any call to it would reload the gear groups currently. I usually "fix" this by force reloading the outdated resource as you mentioned above. I filed https://issues.jboss.org/browse/OSJC-130 for the missing caching even though it's very unlikely that we'll ever resolve it (moving to v3 client lib ahead)