Adding basic test for User creation via API.

The following changes add a basic test for the creation of Users via the
API layer. More tests will be added in the near future.
#1081 should allow you to trim down this code. For example:

```python
@data(
    orm.StringField(str_type=['alpha']).get_value(),
    orm.StringField(str_type=['alphanumeric']).get_value(),
    orm.StringField(str_type=['cjk']).get_value(),
    orm.StringField(str_type=['latin1']).get_value(),
)
```

Remember that, by default, `StringField().get_value()` generates strings between 1 – 80 characters inclusive.