Change system role selection to tag field

Change these check-boxes for system roles to use a tag field instead.

Place the following text below them:

EN: For more information about the roles[ see documention.|https://confluence.translate5.net/display/CON/System+roles]

DE: Mehr Info über die Rollen siehe Dokumentation.

And link "see documentation" with https://confluence.translate5.net/display/CON/System+roles

Remove the existing tool-tip and the "i" icon after the "System roles" label.

Also please change the text for "Enable task-overview" in brackets as shown in the following screen to this

Please change text in brackets to:
EN: Relevant only for translate5 installations
that use translate5 with "editor-only mode".
DE: Nur relevant für translate5 Installationen,
die translate5 im "editor-only mode" nutzen