[cle-release-team] Trunk Experimental Build changes

[Maurer, Christopher Wayne]

We had a separate experimental externals setup already, though it hadn't
been updated since 2009.  I copied over the current trunk one and have
added dashboard (per INFRSTR-89).  The externals nightly build has been
switched over to this and has been rebuilt.  So, we're all set to add more
projects and have them included in the build.

Chris