Correct bug with instantiating _local_context as a thread.local.

_local_context is initialized within the init context method.  This is
causing the thread local to be incorrectly initialized and
consequently get corrupted.
Merge pull request #57 from WebFilings/context_init_error

Correct bug with instantiating _local_context as a thread.local.
Merge pull request #51 from johnlockwood-wf/config

Add configuration module
Split _parse_yaml_config into loading and parsing parts

In order to be more flexible and easily unit testable, split the loading
of the furious.yaml and the parsing of the yaml into two separate
functions.  This will reduce the required patching of file loading stuff
required, and make it possible to support other config loading
mechanisms.