Lumber jack logging

- Change logging to CocoaLumberJack
- Log using custom contexts and macros
- Document to describe creating loggers & filters, adding loggers to CocoaLumberJack, custom macros

Any thoughts on the number of logging contexts?

Feedback on the logging document will be greatly appreciated 

To do this, a custom formatter needs to be implemented: see (or other appropriate punctuation like a dash, comma etc)