Add button styles to admin request edit page

- Danger button for permenantly destroying request
- Primary button for saving changes
Emphasise the dangerous edit request actions
Add ttf-bitstream-vera to package lists.

Closes #618
Add comma delimiters to request numbers on the front page

Originally implemented in 67a8be372ffcbe943ce33c2e55c9a560588ef6fe but lost over time.
Use each instead of for
Add visible_request_count to /version.json
Add confirmed_user_count to /version.json
Fix typo on /request/upload_response

This fixes a typo which cased the following to be displayed when
uploading a response:

    Respond to the FOI request 'FOI Request'FOI User

It now says (correctly):

    Respond to the FOI request 'FOI Request' made by FOI User

Thanks to Ben Fairless for the original implementation of this commit.
Minor tidying of PublicBodyController#list

Spacing, parenthesis, etc
Support simple searching of bodies by short_name
Define track things constraint correctly

> The constraint fk_track_request_public_body on
> track_things_sent_emails is defined incorrectly, referring to user_id
> rather than public_body_id.

Via Robin Houston
Fix typo disable_constraints => constraint_disabling

This connection param is consulted in config/initializers/alaveteli.rb to see whether to load our patch for constraint disabling from lib/no_constraint_disabling.rb
Merge branch 'fix-install-typo' into rails-3-develop
Merge branch 'features/618-ttf-bitstream-vera' into rails-3-develop
Fix typo in password change email subject.
Merge branch 'issues/1460-search-body-by-shortname' into rails-3-develop
Merge branch 'issues/1510-upload-response-typo' into rails-3-develop
Rake task for cleaning up holding pen events
Merge branch 'feature/1407-cleanup-holding-pen' into rails-3-develop
Merge branch 'rails-3-develop' of ssh://git.mysociety.org/data/git/public/alaveteli into rails-3-develop