Updating donate links on the errors page.

Switching all of the links to use the donatewiki redirector.  It takes care
of geolocation and browser langauge detection, so the same URL works for all
languages.  If the entire cluster is down, this link will not work (although
neither would have the old link).  Theoretically this could be fixed with
a single step donation form on the payments cluster, but we currently do
not have such forms.

Also adding tracking information so that we can track donations that come
in as a result of downtime.

Change-Id: I25e7d87871af943175e7cc4568ff8509df95ab06
Merge "Updating donate links on the errors page."