webapp: Fixed visual glitch in xmpp pairing.

It seems that all other uses of <div .col-sm-9> occur outside of
<div .content-box>. This one occurred inside it, when xmpp pairing.

This was introduced in the bootstrap 3 conversion.

templates/configurators/xmpp/buddylist.hamlet

@@ -1,4 +1,4 @@
-<div .col-sm-9 ##{ident}>
+<div ##{ident}>
   <table .table>
     <tbody>
     $if null buddies