It's impossible to stop rails 2 loading a newer i18n gem if it is
installed, so go with the flow and use the latest one but override
the interpolation pattern for now.
Rails 3 pulls in i18n version 0.4.1 as a separate gem which then
breaks our code if it is running on a machine with rails 3 installed
as it tries to monkey patch i18n and fails, so this fix allows us
to run on a machine with rails 3 installed.
time.formats in the locale and then looks for the requested format in
that hash, thereby not doing fallback correctly. To make things worse
it then defaults to just using the requested format name as the format...