Change api to return ListedAsset objects that do not contain property data.

This was done to optimise performance on the front-end. During asset rendering most of the time was spent waiting for data from the backend.
Update submodule
Enable gzip compression for Scalatra REST api
Change api to reload and return updated asset when modifying asset properties.
Merge branch 'master' of https://github.com/finnishtransportagency/digiroad2 into optimize_asset_fetching
Merge branch 'master' of https://github.com/finnishtransportagency/digiroad2 into optimize_asset_fetching
Use validity direction and image ids directly from asset and read values from updated asset returned by api.

Also fixed several bugs related to asset property saving.
Merge branch 'master' of https://github.com/finnishtransportagency/digiroad2 into optimize_asset_fetching

Conflicts:
	digiroad2-oracle
	src/main/scala/fi/liikennevirasto/digiroad2/Digiroad2Api.scala
Reload assets after saving all properties to db
Merge branch 'master' of https://github.com/finnishtransportagency/digiroad2 into optimize_asset_fetching

Conflicts:
	UI/src/bundles/digiroad2/bundle/mapbusstop/plugin/BusStopLayerPlugin.js
	digiroad2-oracle
Merge pull request #104 from finnishtransportagency/optimize_asset_fetching

Optimize asset fetching