turning off SLD support

[Kralidis,Tom [Burlington]]

Hi,

For WMS Server, I have had numerous requests/desires from stakeholders
to have SLD functionality turned OFF.  This is because some activities
do not want their maps restyled by an arbitrary user SLD for whatever
reason (lying with maps).  I think this is a valid issue.

I think either a --without-sld type build flag or a "sld_enabled" "0|1"
WEB/METADATA param would do the trick.  What do you people think?  If
there is consensus, I can file a bug.

..Tom