completion block updates and new method

- updated the return values for the TheoNodeRequestRealtionshipCompletionBlock
- added method for updating a relationship with properties
new metadata field support property update

- with N4J 2.1.5 there is a new field for most API model responses "metadata". this has now been added in
- properties can be any "type" of object
fixed typos in init's
refactored tests and added a new test

- deleting a node as been moved to the absolutely last test because you can't delete a node that has a relationship, thus all of those have to finish and I'm new functionality that is dependent on that node
- add test for updating a relationship with properties
Removed commented out test code
added code docs and removed commented out code
removed println
renamed "save*" to "create*" since it is more descriptive as to what it does
minor tweak to group name
update README

- save methods are now create
- added example for updating a relationship