Read-Write JSON Service Registry Implementation

This pull contains a number of enhancements around the JSON service registry, plus a new extension based on its default behavior that is now able to delete/save service definitions back out to the resource file.

1. The Json service registry itself no longer relies on regex patterns to identify service classes. It instead attempts to parse the pattern to figure out which class to instantiate. 

2. The Json service registry is now slightly friendlier to file resources that do not exist at the specified path, or are simply blank. A warning will be issued in said cases but the execution will resume. 

3. Upgraded Jackson dependency to 2.2.2

4. Implementation of `ReadWriteJsonServiceRegistryDao` along with spock tests. Implementation is not transactional, and will not care to be one. 

I will be testing the changes more thoroughly in the coming week, but wanted to make the progress here more visible and explicit in case there is any feedback along the way.