Return IdentityMap from IdentityMap methods
Remove debug line
Correct return type of empty literal collections
Add toUpper and toLower
Merge pull request #2032 from cleishm/collection-type

Correct return type of empty literal collections
Merge branch 'neo4j/2.0-maint' into master
Merge pull request #2033 from cleishm/master-merge-2.0-maint

Master merge 2.0 maint