Multiple namespaces, missing keys raise.

- Multiple namespaces can be provided
- Unknown keys raise when called as methods,
Arranged method visibility to better reveal intent.
Version bump to 0.0.3
Replace mutest with Uspec, reorganize app.
Fixed the problem with namespaces. Made the Exceptions more useful.
Extracting base Exceptions into their own file.
Extracted ConfigOption into its own file.
Extracted all logic out of ConfigModule and into ConfigHelper.
Refactoring, removing unneeded code.
Handling missing methods in a more creative way.
Fixing bug where missing keys weren't raising.
Made ConfigOptions Enumerable.
Recreating each for ConfigOptions, since each_pair might go missing.
Attempting to find the source of a bug.
Rspec rescues certain NoMethodErrors specially.
Version bump to 0.1.0