Type in oc-icon-paperclip class

Fixed type in oc-icon-paperclip class (from paper-clip to paperclip) which meant that the attachment link wasn't showing in backed.
Unify the handling of detailed exception messages
Default value might be an array
Back-end user groups can now be marked to add new administrators by default
Streamline naming of backend user groups
Add description field to backend user group table
Make more room for group descriptions
Merge pull request #833 from mradamwood/patch-1

Typo in oc-icon-paperclip class
Don't force default groups on new admins, this is now handled by the user interface
Add API code field to admin groups
Add code to seeder
Minor
Minor
showExternalParameter -> showExternalParam
Fixes #836
Fixes https://github.com/octobercms/install/issues/59