Introduced Builder Engine class and some refactoring
blah
Moved unit tests to distinct assembly
Switched Kiev references to nuget
Merged Nodes and Core and spin build engin to distinct assembly
Added builder test
Refactored engine tests
Engin test refactoring
Added events to Builder
Refactoring tests namespaces
Introduction of plugin container
Updated to Kiev 1.1.0
Merge branch 'develop'