Add doc support for Floating IPs Bulk extension

Modified:  src/docbkx/api-ref.xml > to render new section
Added: src/wadls/compute-api/src/ext/os-floating-ips-bulk.wadl
Fixes: bug 1074202

Change-Id: Ia4e1e26454126c558c1b5214558350a93acc0db9
Merge "Add doc support for Floating IPs Bulk extension"