Class will read the the specified configuration file via the property-file parameter.
It accepts the name of the property file to read and the properties to set to
the sitemap scope. For example:
<map:act type="PropertyFileReader">
<map:parameter name="property-file" value="/absolute/path/to/property/file />
<map:parameter name="some.property" value="some_property" />
...
</map:act>
Will place the value of the "some.property" property in the "some_property" variable to be
used in the sitemap using the {some_property} syntax.