Adding API doc links to OMERO docs front page
ant: Default all properties and handle empty vars in conf.py
Merge pull request #758 from hflynn/rebased/develop/api-links

Adding API doc links to OMERO docs front page (rebased onto develop)
ant: Correct property defaults
Merge pull request #766 from rleigh-dundee/ant-propertydefaults

ant: Default all properties and handle empty vars in conf.py