Have a beautiful register page

Change-Id: I5162248afc3b21a1093feaf1078fc401330f0658
Use select2 for timezone selector

Change-Id: Idcb2d6dc1a88c9e11a7559e5d950f19f63fcd5de
Merge remote-tracking branch 'gerrit/6414_have_a_beautiful_register_page' into tuleap-stable-master

* gerrit/6414_have_a_beautiful_register_page:
  Use select2 for timezone selector
  Have a beautiful register page

Change-Id: I5324bd9f760fd971135406e7edcb6b2beb720fa6
Tuleap 6.12.99.5

Change-Id: I0c0883637a77c7c1731b07a630db6574e0882ede