Fixes for 0.6.0

[stellasia]

Small fixes after manual tests:

• Fix relationship type selection (r:RELATIONSHIP doesn't seem to be valid Cypher)
• Make sure we show the layer name in the layer control and not the ukey which is meaningless for the user TODO: fix couple more issues (I, @nikita03565 , will handle this):
• app crashes when there are no nodes found
• app crashes when db with name saved in local storage no longer exists

Prepare for 0.6.0 release:

• Version bump in packages.json
• Update release notes