Switched from the attribute-style of model, inheriting from object, to a
model inheriting from UserDict.IterableUserDict.

The reason for was because there was absolutely no clean way to safely
mix the use of class attributes (the `fields` attribute) and instance
attributes without running into infinite recursions due to overriding
the object.__setattr__ and object.__getattr__ methods.
Added a gitignore rule for the env/ directory.
Bumped the version number to 0.2.0.
Added some examples.
Switched the change_user.py example to use the dict-style key
references, instead of the attribute-style accessors.
Another teeny-tiny fixup with one of the examples.
Re-aligned the SETTINGS dict in setup.py.
Fixed up a few more, small bugs in the examples, and switched to calling
`print` like a function: `print()`.
Yeah, these allergy meds are taking a toll on the brain.
Updated the README.
Merge branch 'release/0.2.0'