Introduce "icmp" option for security group rule

[OpenStack Infra]

https://review.openstack.org/214056
Dear bug triager. This bug was created since a commit was marked with DOCIMPACT.
Your project "openstack/trove" is set up so that we directly report the documentation bugs against it. If this needs changing, the docimpact-group option needs to be added for the project. You can ask the OpenStack infra team (#openstack-infra on freenode) for help if you need to.

commit 1584f198a5d92de172e878282274de5661a076f1
Author: Masaki Matsushita <email address hidden>
Date: Fri Aug 14 16:45:21 2015 +0900

    Introduce "icmp" option for security group rule

    This change introduces new datastore option "icmp" to
    configure whether to permit ICMP. It helps users to
    check DB instance health in different way from access
    DB ports.

    DocImpact
    Closes-Bug: #1485884
    Change-Id: I61edeb38ded5543b7976a01363108a7b5b4fc5b5