Missing send() on ServerMetaData in method

Hi,

i just wanted to delete some metadata but found out that nothing happens.
Seems that the send() finalization is missing in the delete() in 
php-opencloud/lib/OpenCloud/Compute/Resource/ServerMetadata.php.

When i put some send() at the end it´s working like expected.

Would be nice to have this fixed.

Thanks a lot & best regards
M. Strojek
