save with label: update node.save documentation
save with label: add test for saving with label
save with label: implement saving with a label
save with label: add test for saving multiple nodes with a label
batching: make it possible to asynchronously add callbacks to a transactions commit
save with label: use safeBatchCommit
save with label: test atomicity of node&label saves
save with label: throw error if attempted in batch mode
catch input errors in batches
save with label: add test for error if attempting to save & label in batch mode
save with label: overt warnings about using node.save in a batch
0.9.4