Fix two bugs in keystone module

This pull-request fixes a problem introduced in 64740ea1 that caused settings loaded from configuration profiles to be ignored by the `auth` method of `salt.modules.keystone`.

As 64740ea1 mentioned the mysql module as a basis for the design, I've also updated `auth` so that if some (but not all) of the needed parameters are in `connection_args` it loads the rest from the configuration or configuration profile (if possible). This is consistent with mysql's behaviour.

Also, the following typo appeared in 30e398fc:

```python
    kwargs[insecure] = True
```

This should have been:

```python
    kwargs['insecure'] = True
```