Introspector does not preserve capitalized columns name
The introspector "python-izes" the column names by default. So if you have such a table, the actual field definition will look something like:

```python
dept = TextField(column_name='Dept')
```

In this way, the actual underlying column-name is still preserved and used, it's just that the accessor for it conforms to a Pythonic naming convention.

If you want to use the column-names as-is, you can pass `literal_column_names=True` to the `introspect()` or `generate_models()` methods.
Given a simple table like

```python
class Table(Model):
    employee = CharField(unique=True)
    Dept = TextField()
```

On the attempt in trying to introspect this table `models = Introspector.from_database(db).generate_models()`, the keys in `models['Table'].__dict__` are all lowercase:

```python

>>> models['Table'].__dict__
# psuedo output
mappingproxy({...,
'employee': <peewee.FieldDescriptor at 0x7f480108c748>,
'dept': <peewee.FieldDescriptor at 0x7f480108ceb8>, # want 'Dept' got 'dept'
...})
```

** Is there any way to preserve capitalized object names?**

---

The reason why I need this is because of such an insert statement:

```python
data = {
'employee' : 'John Smith'
'Dept' : 'Accounting'
}
Table.insert(**data) # or Table.create(**data) getting two different errors weirdly.
```
