Fixed bug in MNode.R where we failed to save the capabilities to the node after doing the lookup.
Fixed MNode test to set the expected data type to be data.frame.
Implement serialization of accessPolicy in SystemMetadata.
Clarify that remaining TODO is low priority.
Add tests to verify accessPolicy serialization.
Merge branch 'master' of github.com:DataONEorg/rdataone
Merge branch 'master' of github.com:DataONEorg/rdataone
merged changes from master upstream