models: Add Project.get_properties
models: Add Project.get_properties

Counterpart of Message.get_properties

Signed-off-by: Fam Zheng <df9fd617995bad07eac70e27aa3fe5069270e3bd@redhat.com>

patchew-project/patchew,famz/patchew,patchew-project/patchew,famz/patchew,patchew-project/patchew,famz/patchew,patchew-project/patchew,famz/patchew