Add support for dynamic labels.

[michael-simons]

Things basically work, but need a lot of love:

• Tests for the reactive world
• Test for nodes with dynamic labels inside relations
• Maybe @Wurstsalat can be improved along with some other naming.

[michael-simons]

Not only are tests for reactive missing, actually the whole implementation for it ;)

Also the implementation on the save of related nodes.

[michael-simons]

Relationships are handle now.

Missing as well: Validation of Wurstsalat:

• Only one in hierarchy
• No property with the same name being created on the node