Bug 20921: Add borrowernumber and branchcode as html attributes

Bug 20921: Add borrowernumber and branchcode as html attributes

To test:
1 - Apply patch
2 - Visit the opac
3 - Sign in
4 - You should not see any difference
5 - Inspect the element  'Welcome, {username}'
6 - Note the attributes for borrowernumber and branchcode
7 - Add to OPACUserJS:
$(document).ready(function(){
    console.log( $(".loggedinusername").attr('data-branchcode'));
    console.log( $(".loggedinusername").attr('data-borrowernumber'));
});
8 - Check the console and note you can see the info expected

Signed-off-by: Maryse Simard <maryse.simard@inlibro.com>
Followed the test plan and it works.

Signed-off-by: Jonathan Druart <jonathan.druart@bugs.koha-community.org>
Signed-off-by: Nick Clemens <nick@bywatersolutions.com>