Use Json for configuration files

This patch converts the current configuration files to json and uses the python json library to parse the them. Json is a standard format and as such already has many encoders and decoders available. This option also leaves room for a schema validation using something like jsonschema.

Additionally, the presence of the string type checks prevents unicode strings from being parsed correctly and to remedy this, they have been removed. Python recommends duck typing over strict type verification.

Finally, full schema validation is done against the configuration data upon load to detect and emit errors regarding type differences and structural requirements.

It's worth mentioning that this patch introduces a the jsonschema package dependency.