* [presubmit] Enforce language attribute in projectt.yaml to be always set.
* Update documentation, better presubmit check, new project template.
* add docstring to templates.py
* Add example values in the project.yaml template and remove python value for now
* Add "project: c++" to 256 projects
* format
* Add labels and selective_unpack sections to the presubmit check
* fix incorrect auto_ccs format in three projects
* fix nss emails after rebase
PostGIS depends on GEOS, and recently requres GEOS 3.6 which cannot be found in ubuntu 16.04.
With this change build will pull newest GEOS 3.7 from Ubuntu 19.04.