- fixed memory leak for Datasrc* stored in the MetaDataSrc vector.
  there are several possible ways to do this, but I chose to using
  boost::shared_ptr.  expect for portability issues this seems to be the
  cleanest solution, and, regarding portability, we already heavily rely on
  boost anyway, so we should revisit the whole design if/when we seriously
  consider binary portability.


git-svn-id: svn://bind10.isc.org/svn/bind10/trunk@1118 e5f2f494-b856-4b98-b285-d166d9295462