[Merge] lp:~robert-ancell/ubuntu-touch-session/lightdm-config into lp:ubuntu-touch-session

[Robert Ancell]

Note - this requires LightDM >= 1.15.0
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https://code.launchpad.net/~robert-ancell/ubuntu-touch-session/lightdm-config/+merge/267286
Your team Ubuntu Phablet Team is requested to review the proposed merge of lp:~robert-ancell/ubuntu-touch-session/lightdm-config into lp:ubuntu-touch-session.