PCP : Notify supporter when their PCP status is changed by site admin

Rationale
------------
Default behavior for PCP's is that they "require approval" by a site admin. Currently there is no way for the creator of the PCP to know when their page has been improved (and hence when they can start promoting their page to friends, etc.)

Implementation
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1. Modify the function which set's civicrm_pcp.status_id (I think this is Contribute/BAO/PCP setIsActive() ) to trigger sending an email notification to the PCP "owner's" (e.g. civicrm_pcp.contact_id) primary email whenever the status is changed.

2. Post process should set a status message to be displayed on top of the page (currently it does not do this). Status should say:
"$pcpPageTitle status has been updated to $newStatus. Notification has been sent to the supporter at $supporterEmail."

3. Create a new email template - PCPStatusChange - which is sent on status change. Content of the email is:

Subject: Your Personal Campaign Page for $contribPageTitle

Body (note: some of below is pseudocode - not necessarily exact implementation):

========================
Your Personal Campaign Page
========================

{if $newStatus EQ 'Approved'}

Your personal campaign page has been approved and is now live.

Promote your fundraising page:
>> $pcpTellFriendURL

View and update your page:
>> $pcpInfoURL

Questions? Send email to:
>> $pcpNotifyEmailAddress

{elseif $newStatus EQ 'Rejected'}

Your personal campaign page has been reviewed. There were some issues with the content
which prevented us from approving the page. We are sorry for any inconvenience.

Please contact our site administrator for more information:
>> $pcp_block.notify_email

{/if}