fix(login): check that password is non-empty or null to avoid crash

SoObjects/SOGo/SOGoWebAuthenticator.m

@@ -148,6 +148,11 @@
     return NO;
   if(_login && [_login length] == 0)
     return NO;
+  
+  if(!_pwd)
+    return NO;
+  if(_pwd && [_pwd length] == 0)
+    return NO;
 
   loginDomain = nil;
   if(*_domain == nil || [*_domain length] == 0)

UI/MainUI/SOGoRootPage.m

@@ -1218,7 +1218,7 @@ static const NSString *kJwtKey = @"jwt";
      response = [self responseWithStatus: 403
                               andString: @"Missing 'oldPassword' parameter"];
     }
-  else if (!newPassword)
+  else if (!newPassword || (newPassword && [newPassword length] == 0))
     {
      response = [self responseWithStatus: 403
                               andString: @"Missing 'newPassword' parameter"];