Only require Apt::Pin elasticsearch for ubuntu
Only require Apt::Pin elasticsearch for ubuntu

This requirement on Apt::Pin caused jessie to fail provisioning
elasticsearch. Flip the dependency around so it's only necessary
for ubuntu.

Change-Id: Ib828e473a0ff2c64fe96cec03e8044002fba2c0f

wikimedia/mediawiki-vagrant,wikimedia/mediawiki-vagrant,wikimedia/mediawiki-vagrant,wikimedia/mediawiki-vagrant,wikimedia/mediawiki-vagrant,wikimedia/mediawiki-vagrant