(Bug 3994) : New "deleted account" page

* Shows an initial paragraph according to your relationship with the
   account and whether it is a community

* Shows the reason for deletion if there is one

* Shows the bit about being notified upon purge if you are logged in and
   are not the owner/admin.
(Bug 3994) : Don't offer to track protected usernames.
(Bug 3994) : Now show "relationship text" & link.

If the user has granted access to or subscribes to or is a member of
the deleted account, tell them this and offer a link to change that.
(Bug 3994) : Tidied up indents, removed trailing spaces
(Bug 3994) : Changes as requested in code review

* Cleanup of spaces & linebreaks

* Changed $dbr to $dbcr

* Only look up the deleter in the db when it's a community

* Tweak to page formatting
(Bug 3994) : Changed interpolated variables to bound params in db query
(Bug 3994) : Corrected SecurityAttributeChanged.pm for best practice as per pull request comments

* Changed $dbr to $dbcr for cluster reader

* Changed interpolated variables to bound parameters in db query.
(Bug 4719) Coerce all false values to the numerical 0

We can't rely on defined-ness. The cached value is stored as an empty
string when there are no points, so it fails the defined test and
doesn't get set to 0. Then in the frontend it gets printed as an empty
string...

This means that on production, or anywhere else with memcache on, first
time you load the page you'll get "you have 0 points". On subsequent
loads it becomes "you have points". Misleading! Annoying! Weird.
Merge pull request #195 from swaldman3/3994_deleted_account_pages

Bug 3994 : deleted account pages
Merge pull request #205 from afuna/disappearing-zero-bug4719

(Bug 4719) Coerce all false values to the numerical 0