Add links section to the stacks index response

Add a `links` section to the stacks index response that will contain
pagination links for the collection - this commit includes adding a
`next` link to the section.

blueprint pagination
Change-Id: I76451a101e7c417a485da78dd7fb19229d91861d
Add exact filter support to SQL API list stacks

Uses a dict of KEY:VALUE to compare values of VALUE against database
attribute KEY and return matching stacks.  If VALUE is a list, tuple,
set, or frozenset, this will evaluate to an IN clause instead.

blueprint: filter-stacks
Change-Id: If68edd9eaad3fe2ec4d11831d9eda9798a490e89
Add filter support to stack API

Accepts multiple request params ATTR=VALUE to filter the listed
stacks.  Stacks will be matched against all whitelisted filters
passed in the request.  Whitelisted filters for stacks are NAME
and STATUS.

If the same ATTR is passed multiple times, stacks matching ANY of the
values will be returned.

blueprint: filter-stacks
Change-Id: Ic9421a827e99793448c23a841006fb8c03819030