Add api method that returns possible values for enumerated properties of given asset type.
Merge branch 'master' of https://github.com/finnishtransportagency/digiroad2

Conflicts:
	digiroad2-geo/src/main/scala/fi/liikennevirasto/digiroad2/feature/FeatureProvider.scala
	digiroad2-oracle
	src/test/scala/fi/liikennevirasto/digiroad2/Digiroad2ApiSpec.scala