LifeCycle feature

LifeCycle feature
As same as amazon S3 interface,"PUT Bucket lifecycle" and
"DELETE Bucket lifecycle" have been implemented,
"GET Bucket lifecycle" not realized yet as S3cmd has not
realize it also.
The feature`s main point is to remove expire file per day.
Files transfer from hot layer to cold layer is not supported.
ToDo:Maybe to transfer from replicate pool to EC pool or
from ssd to sata pool will be valuable.

Now put all buckets which should do lifecycle into shard
objects in .rgw.lc pool.

lifecycle config file format:
<LifecycleConfiguration>
    <Rule>
        <ID>sample-rule</ID>
        <Prefix></Prefix>
        <Status>enable</Status>
        <Expiration>
           <Days>1</Days>
        </Expiration>
    </Rule>
</LifecycleConfiguration>

Signed-off-by: Ji Chen <insomnia@139.com>