Correct the default value for PE version

The default value in the documentation was wrong; this updates it to reflect
the current builds.

Signed-off-by: Daniel Pittman <daniel@rimspace.net>
Use generic installer from upstream PE build

Newer PE builds have introduced a generic installer script, able to do
platform tag extraction for us.  This is much more generic than the code we
hand-managed, so we can reduce our broker install script to simply download
and delegate to that script.

Signed-off-by: Daniel Pittman <daniel@rimspace.net>
Better error detection when using curl to download script

curl, by default, will return successfully even if the server sends back some
error codes that -- in practice -- we really want to fail.  This bumps it over
to exiting with error on more of those failures, and hopefully getting less
confusing apparently success.

Signed-off-by: Daniel Pittman <daniel@rimspace.net>