global: grunt fixes for jquery-ui

* Installs jquery-ui instead of just jquery.

* Updates jquery-ui version to 1.10.4.

Signed-off-by: Kamil Neczaj <kneczaj@cern.ch>
Reviewed-by: Georgios Kokosioulis <georgios.kokosioulis@cern.ch>
Tested-by: Jiri Kuncar <jiri.kuncar@cern.ch>
utils: json import fix

* Imports the actual json module instead of
  looping import of utils/json.py.

Signed-off-by: Kamil Neczaj <kamil.neczaj@cern.ch>