Added option to disable Peer Verification in EBox::RESTClient
Improve doc for conf setting

As expected from current behaviour
Make use of VerifyPeer to false

On EBox::RESTClient as we don't verify other HA hosts
Depend on latest version of core to work
Merge pull request #1475 from Zentyal/ejhernandez/rest-non-verification

Perform no certificate peer verification in HA scenario