Updated field regex

Catches field type as first argument.
Throws exception if a model is not passed to the constructor as this
lib would be kinda useless without a model.
All columns don't have field values

Let's not die when one of those are parsed shall we
Nest conditions

Prevent unnecessary condition checks.
Set custom labels

Added functions to set new labels on fields.
Force type and change label.

Overwrite the default label created from the column name.
Force a form field to be of a certain type. TODO: validate that the
specified type is valid for the columns data type.