Refactoring

[johnomotani]

Some things that would be nice to do to make this package easier to work with in other codes:

• Merge CerfonFreidberg and CerfonFreidbergSymmetric into a single class, just have a setting to switch between the different solutions.
• Instead of setting up the solution with arguments to .init() method, define the settings using OptionsFactory (see for example the use of OptionsFactory in hypnotoad), and replace the init() methods with a constructor __init__(self, settings) that takes a dict that is passed to the OptionsFactory instance (and could be loaded from a YAML file, etc.).