TEIIDDES-2341: Ensures Server view is fully refreshed on start of server

* TeiidParentServerListener
 * A timing issue can occur when starting a jboss server through Eclipse
   (rather than just connected to one externally). The STARTED event is
   sent before the server has actually finished starting!
 * When a starting event is received, create a new thread that polls the
   server to see if Teiid is available. Only when the parent is connectable
   will an attempt be made to connect to the teiid instance.
 * This means a slight delay in seeing the teiid instance contents in the
   server view but will be fully populated once the parent server and
   instance are fully available.

* DqpUiPlugin
 * Removes the shutdown of the server and preview manages since both are
   shutdown by the DqpPlugin and the code is generating SWT errors since
   the display has been destroyed etc...