Removing seed now data migration is done

It was using the TagRepository to put the tag data, as the TagRepository has been removed and this is a data migration I think it can be removed now.
Remove TagRepository
Upgrade Rails to 3.2.11

Include xml_parser disabling.
Bump depended-on version of lograge

lograge < 0.1.0 is incompatible with rails >= 3.2.9 (see
roidrage/lograge@1b4767f4).
Merge remote branch 'origin/remove_tag_repository'
Upgrade to new permissions format
Disable limited exception pages in production

Rails has a default of showing limited exceptions in production, IF it thinks
the request is local/from a trusted proxy (and not being proxied from the
internet). Our infrastructure is telling apps that all requests actually come
from trusted proxies, even though they don't, hence our problem.

A wrinkle is that we have apps that are talking to each other, so it's
conceivable that information could get from an inter-app request that errored
and then be displayed to the outside world.

The problem would be limited if the proxies set the headers correctly, but
eliminated if we set config.action_dispatch.show_exceptions to false.

Nick has dealt with the problem in such a way that prevents exception
information being shown, but which also hides helpful 4xx and 5xx messages
(eg if you don't have "signin" permission for an app, you get a 403 and
explanatory HTML, but now it gets clobbered). I'm sure there are other cases.
Ignore invalid user records in migration

They might be invalid for other reasons (eg they have been around for longer
than a given validation that it fails).
Merge pull request #49 from alphagov/upgrade_to_new_permissions_format

Upgrade to new permissions format
Merge pull request #50 from alphagov/disable_limited_exception_pages_in_production

Disable (limited) exception/debug pages in production
Merge branch 'master' into bump-plek

Conflicts:
	Gemfile.lock