Add option 'show record options' to Site, refs #986

This option will be used to show or hide the options dialog when the user
clicks on the button to start a new conference.

Also cleaned up the views site/show and site/edit, moving the strings to their
appropriate places in the locales.
Set the record flag automatically when starting a conference, refs #986

If the option `webconf_auto_record` is set, the record flag will be set
automatically according to the user's permission to record in the target
room.
The `join_options` dialog is only shown if the flag is not set, otherwise
the user is redirected directly to the conference.