ACTION-18: Inform person who proposed a group that the group is proposed, and to follow comments

Idea is to inform (by direct email) the person who proposed the group. In that email we should say, roughly:
*your group is shown as proposed
*people can show their support and if there is enough we will approve it
*people may also leave comments about the proposal that you should read here <URL>
*if approved you will receive notification

[dom]: need input from ACTION-51

[dom]: see http://codex.wordpress.org/XML-RPC_WordPress_API/Posts#wp.getPost for getting URL for proposed CG blog post

see
https://www.w3.org/2011/06/proposed_groups/templates/changed_to_proposed_group_ack.tpl

Done via

https://cvs.w3.org/Team/WWW/Systems/lib/php/proposed_groups.phi.diff?r1=1.165;r2=1.166