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