Drupal 7.56 hardcoded

[spficklin]

We need to upgrade the rapid install script so that the 7.56 version is not hard-coded and it pulls the most recent version.

[shawnawsu]

@spficklin I don't see how this would be achievable given that drush dl is deprecated in Drush 9. We'd have to require users to have an older version of drush which isn't ideal, especially if you're running other sites which are D8+. Drush dl is deprecated in favour of installing with composer, so we'd have to require users to also install composer which seems less than ideal than just specifying the version in a wget.

We can update it as new versions come out and it most definitely needs to be updated now since it's pointing to an old version with the security flaw. But the pull request from Abdullah completely rewrites this repo so I'm happy to hand maintenance of it over to them. :)