Decouple totp from users table by moving to totp_credentials table

* this allows implementation of other mfa schemes in the future (webauthn)
* also makes key management easier and enforces one totp credentials per user on db-level

management/templates/index.html

@@ -93,7 +93,7 @@
                 <li class="dropdown-header">Advanced Pages</li>
                 <li><a href="#custom_dns" onclick="return show_panel(this);">Custom DNS</a></li>
                 <li><a href="#external_dns" onclick="return show_panel(this);">External DNS</a></li>
-                <li><a href="#two_factor_auth" onclick="return show_panel(this);">Two Factor Authentication</a></li>
+                <li><a href="#two_factor_auth" onclick="return show_panel(this);">Two-Factor Authentication</a></li>
                 <li><a href="/admin/munin" target="_blank">Munin Monitoring</a></li>
               </ul>
             </li>

management/templates/login.html

@@ -72,7 +72,7 @@ sudo tools/mail.py user make-admin me@{{hostname}}</pre>
     </div>
     <div class="form-group" id="loginOtp">
         <div class="col-sm-offset-3 col-sm-9">
-          <label for="loginOtpInput" class="control-label">Two Factor Code</label>
+          <label for="loginOtpInput" class="control-label">Two-Factor Code</label>
           <input type="text" class="form-control" id="loginOtpInput" placeholder="6-digit code">
         </div>
     </div>

management/templates/two-factor-auth.html

@@ -31,7 +31,7 @@
     }
 </style>
 
-<h2>Two Factor Authentication</h2>
+<h2>Two-Factor Authentication</h2>
 
 <div class="twofactor">
     <div class="loading-indicator">Loading...</div>