Use ES2.x for searchlight tests
Use ES2.x for searchlight tests

Searchlight project will be switching over to
elasticsearch version 2.x. This change will
install the 2.x version for running tests.

Closes-Bug: #1582316

Change-Id: I34eb451cea6f9c0eced9243f7267969dec1f78f5

Tesora/tesora-project-config,dongwenjuan/project-config,Tesora/tesora-project-config,openstack-infra/project-config,openstack-infra/project-config,dongwenjuan/project-config