added 'show neighborhood' node context action

opens faceted search dialog to add edges from the knowledge neighborhood
of selected nodes

todo; web api calls are slow

todo; web api calls should be made async

refs #1
remove application of layout after expand nodes

refs #2
fix for handling subject-only statements

refs #1
added entities as a knowledge neighborhood facet

refs #1
changed dialog title to Knowledge Neighborhood

refs #1
filter down selected nodes by linked

also updated node filtering before "Expand Node" action

refs #1