Remove references to redirection_date

- Remove the redirection_date line from the generated file from the
  new_site rake task.
- This is part of reconfiguring transition to be the canonical source of
  redirection (transition) dates, in an attempt to keep them up to date
  without developer intervention.
Remove the redirection_date line from all existing site YAML

I paired with @rjc123 on this to do it in a script rather than me
spending quite a while removing them manually:

`while read line; do grep -v redirection_date $line >
site_list_redirection_date.txt; mv site_list_redirection_date.txt $line;
done < site_list.txt`
Adjust mcga site config to accommodate rules
Merge pull request #945 from rjc123/master

Config additional monitor aliases
Merge pull request #918 from alphagov/remove_transition_date_from_config

Remove references to redirection_date
Merge pull request #946 from rjc123/master

Config Charity Commission aliases
Merge pull request #942 from rjc123/newmappings

Adjust mcga site config to accommodate rules
Merge pull request #947 from rjc123/master

Add transportdirect.info aliases
Configure transport direct new home page
Change Transport Direct site title and add global redirect