BUG: Fix MacOSX packaging

This commit ensures the MacOSX packaging script is executed last
by installing the 'Runtime' component last and should ensure the
packaged Slicer application can be executed without crashing.

This particular issue was introduced by commit r23158 where two
things happened:

(1) updated of the build system to explicitly install Slicer components.
The component where specified in the order 'Runtime', 'RuntimeLibraries'
and 'RuntimePlugins'

(2) the MacOSX packaging script was associated with the 'Rumtime' component

The consequence was that Slicer libraries and plugins where installed after
the script was executed and the plugins and libraries where no properly
fixed up. It then prevented the Slicer application from being executed.

git-svn-id: http://svn.slicer.org/Slicer4/trunk@23183 3bd1e089-480b-0410-8dfb-8563597acbee