ec2: use SecurityGroup object

Convert one place in the ec2 API code that was using the db API
directly to get a security group.  Use the SecurityGroup object for
this instead.

Some test fixes were needed to account for fields that the
SecurityGroup object does not have set as nullable.

Change-Id: I4b15b6bcb35f95955911a48faa8d74f6167593a0
ec2: use BlockDeviceMappingList object

Convert a direct use of the db API with the nova object equivalent.
Some test fixes were needed to include fields the object expects to be
preset in the fake db objects.

Change-Id: I1d562aa2535af9e713c6486c5c50a2ffe625c198
GET details REST API next link missing 'details'

When executing a pagination query a "next" link is included in the
API reply when there are more items then the specified limit.

See pagination documentation for more information:
http://docs.openstack.org/api/openstack-compute/2/content/
Paginated_Collections-d1e664.html

The caller should be able to invoke the "next" link (without
having to re-format it) in order to get the next page of data.
The documentation states "Subsequent links will honor the
initial page size. Thus, a client may follow links to traverse
a paginated collection without having to input the marker parameter."

The problem is that the "next" link is always scoped to the
non-detailed query.

For example, if you execute "/v2/<tenant>/servers/detail?limit=1",
the "next" link does not have the URL for a detailed query and is
formatted as "/v2/<tenant>/servers?limit=1&marker=<marker>". In this
case the "next" link needs to be scoped to "/v2/<tenant>/servers/detail".
Common code is used for both the v2 and v3 APIs.

Existing test cases will be updated to verify that the next link is
correctly scoped for both the v2 and v3 APIs.

The user could work around this issue my manually inserting '/details'
into the "next" link URL.

Change-Id: Ib06a6cc6e2dd5e2c8c16986ee256a58752626eb9
Closes-bug: 1299247
Merge "ec2: use SecurityGroup object"
Merge "ec2: use BlockDeviceMappingList object"
Merge "GET details REST API next link missing 'details'"