GML: allow to specify geometry property name in .gfs file

git-svn-id: https://svn.osgeo.org/gdal/trunk@27132 f0d54148-0727-0410-94bb-9a71ac55c965
Add Vagrantfile

git-svn-id: https://svn.osgeo.org/gdal/trunk@27133 f0d54148-0727-0410-94bb-9a71ac55c965
Merge branch 'trunk' into trunk_travis_macosx