New MAP metadata

I hace decided to use the same strategy of "is the layer queryable" but this time to the WCS so that users can download the layers, by simplely clicking in a small icon

The first thing is that information concerning the layer is has to be indicated in the MAP file as metadata and then retrived by kamap

Now the MAP file to have a WCS layer downloaded by the Kamap needs the following metadata

METADATA
"download" "true"
END