First draft of the plugin descriptor changes for "special destinations" ...

First draft of the plugin descriptor changes for "special destinations" support in bundles,

which are going to enable using specialized bundle deployers not necessarily
using file system and a "base path" to do their deployment.

An example bundle target:
<bundle-target>
   <destination-base-dir name="Deploy Directory" description="The deployment directory for a standalone server">
      <value-context>measurementTrait</value-context>
      <value-name>deployDir</value-name>
   </destination-base-dir>
   <special-destination name="Patch Installer" description="Accepts JBoss AS patches and installs them to a standalone server" bundle-type="JBoss AS Patch Bundle">
      <value-reference reference-name="host" context="pluginConfiguration" name="hostname"/>
      <value-reference context="pluginConfiguration" name="port"/>
      <value-reference context="pluginConfiguration" name="user"/>
      <value-reference context="pluginConfiguration" name="password"/>
   </special-destination>
</bundle-target>