Finish a working implementation of configuration loading

* handles yaml file loading
* handles environment based loading and a default env
* handles recursive directory file loading
* provides automatic loading of files or on load! call
* can reload files after changing data via reload!
* Use locks for ensuring thread safety
* allow setting of global constant accessor

PENDING:
* Add Tests, especially for edge cases (deep dir structures, many threads)
* Add ability to configure a backend loader via plugin/gem. (json, xml)