method signatures in db/sqlalchemy/api.py does not match its base method

[Accela Zhao]

I found in db/sqlalchemy/api.py that there are several methods whose signature does not match its base, for example, https://github.com/openstack/magnum/blob/master/magnum/db/sqlalchemy/api.py#L140 (commit e5f78263)

```
def get_bay_list(self, context, filters=None, limit=None, marker=None,
                                   sort_key=None, sort_dir=None):
```

It missed `columns=None` from the base method signature at https://github.com/openstack/magnum/blob/master/magnum/db/api.py#L44

```
def get_bay_list(self, context, columns=None, filters=None, limit=None,
                                 marker=None, sort_key=None, sort_dir=None):
```

Other occurrences including

    https://github.com/openstack/magnum/blob/master/magnum/db/sqlalchemy/api.py#L310
    https://github.com/openstack/magnum/blob/master/magnum/db/sqlalchemy/api.py#L420
    https://github.com/openstack/magnum/blob/master/magnum/db/sqlalchemy/api.py#L525
    https://github.com/openstack/magnum/blob/master/magnum/db/sqlalchemy/api.py#L621
    https://github.com/openstack/magnum/blob/master/magnum/db/sqlalchemy/api.py#L725
    https://github.com/openstack/magnum/blob/master/magnum/db/sqlalchemy/api.py#L826

Another problem is https://github.com/openstack/magnum/blob/master/magnum/db/sqlalchemy/api.py#L771. Looks like its parent class missed argument `context`.

[OpenStack Infra (hudson-openstack)]

Reviewed: https://review.openstack.org/186387
Committed: https://git.openstack.org/cgit/openstack/magnum/commit/?id=fd34adb8e7e0134363bc467306dc1952946e3f4c
Submitter: Jenkins
Branch: master

commit fd34adb8e7e0134363bc467306dc1952946e3f4c
Author: Accela Zhao <email address hidden>
Date: Mon Jun 1 18:56:09 2015 -0700

    Fix method signatures unmatching in db api

    There are a few method signatures in db/api.py who unmatches their
    children. For example `get_bay_list`

    ```
        def get_bay_list(self, context, columns=None, filters=None, limit=None,
                         marker=None, sort_key=None, sort_dir=None):
    ```

    The argument `columns` is never being respected or used in children or
    elsewhere. After collecting a few opinions we decided to remove the unused
    argument `column` from the base methods in db/api.py.

    Besides, there is another unmatch in db/api.py

    ```
    def get_service_by_name(self, bay_name):
    ```

    It misses argument `context` compared to its only child in
    db/sqlalchemy/api.py. This patch adds the argument `context`.

    Closes-Bug: #1459662
    Change-Id: If4f60661c9cd182d6bbe4539b3c594fb45744874