Add doc support to os-server-password extension

Added doc support to Compute API extension to retrieve / reset admin pass
Modified:   src/docbkx/api-ref.xml
Added:   src/wadls/compute-api/src/ext/os-server-password.wadl
Fixes: bug 1108126

Change-Id: I6dc818a515cf961b76f10b4cd30108d68ffa69f0
Merge "Add doc support to os-server-password extension"