Fix a couple of build problems

1. Fix r3784 where the additional 3pty jars were not being copied into
ant-libs/ by the build file.

2. Fix the following issue:

  http://code.google.com/p/google-caja/issues/detail?id=1134

by changing the default PluginEnvironment of the build service to
rewrite URIs to point to "example.com", which is an RFC-reserved
domain that will never resolve to anything.

[MikeSamuel, 2009-10-07 20:03:40]

LGTM

[ihab.awad, 2009-10-07 20:14:12]

@3786