LRDOCS-364 Added another target that's called by build-properties-docs. The new target gets a list of all the properties HTML files in the dist dir and uses index.ftl to generate index.html. index.html is written to the dist dir.
LRDOCS-364 Added support for specifying a lp.version property so the Liferay Portal version is printed on the index.html, portal.properties.html and system.properties.html files
LRDOCS-364 Added message informing the user to specify their Liferay Portal version as a parameter if their Liferay Portal version is not 6.1
LRDOCS-364 Adjustments to generating index.html